first commit

ppocr/modeling/heads/rec_att_head.py

+# copyright (c) 2021 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import paddle
+import paddle.nn as nn
+import paddle.nn.functional as F
+import numpy as np
+
+
+class AttentionHead(nn.Layer):
+    def __init__(self, in_channels, out_channels, hidden_size, **kwargs):
+        super(AttentionHead, self).__init__()
+        self.input_size = in_channels
+        self.hidden_size = hidden_size
+        self.num_classes = out_channels
+
+        self.attention_cell = AttentionGRUCell(
+            in_channels, hidden_size, out_channels, use_gru=False)
+        self.generator = nn.Linear(hidden_size, out_channels)
+
+    def _char_to_onehot(self, input_char, onehot_dim):
+        input_ont_hot = F.one_hot(input_char, onehot_dim)
+        return input_ont_hot
+
+    def forward(self, inputs, targets=None, batch_max_length=25):
+        batch_size = paddle.shape(inputs)[0]
+        num_steps = batch_max_length
+
+        hidden = paddle.zeros((batch_size, self.hidden_size))
+        output_hiddens = []
+
+        if targets is not None:
+            for i in range(num_steps):
+                char_onehots = self._char_to_onehot(
+                    targets[:, i], onehot_dim=self.num_classes)
+                (outputs, hidden), alpha = self.attention_cell(hidden, inputs,
+                                                               char_onehots)
+                output_hiddens.append(paddle.unsqueeze(outputs, axis=1))
+            output = paddle.concat(output_hiddens, axis=1)
+            probs = self.generator(output)
+        else:
+            targets = paddle.zeros(shape=[batch_size], dtype="int32")
+            probs = None
+            char_onehots = None
+            outputs = None
+            alpha = None
+
+            for i in range(num_steps):
+                char_onehots = self._char_to_onehot(
+                    targets, onehot_dim=self.num_classes)
+                (outputs, hidden), alpha = self.attention_cell(hidden, inputs,
+                                                               char_onehots)
+                probs_step = self.generator(outputs)
+                if probs is None:
+                    probs = paddle.unsqueeze(probs_step, axis=1)
+                else:
+                    probs = paddle.concat(
+                        [probs, paddle.unsqueeze(
+                            probs_step, axis=1)], axis=1)
+                next_input = probs_step.argmax(axis=1)
+                targets = next_input
+        if not self.training:
+            probs = paddle.nn.functional.softmax(probs, axis=2)
+        return probs
+
+
+class AttentionGRUCell(nn.Layer):
+    def __init__(self, input_size, hidden_size, num_embeddings, use_gru=False):
+        super(AttentionGRUCell, self).__init__()
+        self.i2h = nn.Linear(input_size, hidden_size, bias_attr=False)
+        self.h2h = nn.Linear(hidden_size, hidden_size)
+        self.score = nn.Linear(hidden_size, 1, bias_attr=False)
+
+        self.rnn = nn.GRUCell(
+            input_size=input_size + num_embeddings, hidden_size=hidden_size)
+
+        self.hidden_size = hidden_size
+
+    def forward(self, prev_hidden, batch_H, char_onehots):
+
+        batch_H_proj = self.i2h(batch_H)
+        prev_hidden_proj = paddle.unsqueeze(self.h2h(prev_hidden), axis=1)
+
+        res = paddle.add(batch_H_proj, prev_hidden_proj)
+        res = paddle.tanh(res)
+        e = self.score(res)
+
+        alpha = F.softmax(e, axis=1)
+        alpha = paddle.transpose(alpha, [0, 2, 1])
+        context = paddle.squeeze(paddle.mm(alpha, batch_H), axis=1)
+        concat_context = paddle.concat([context, char_onehots], 1)
+
+        cur_hidden = self.rnn(concat_context, prev_hidden)
+
+        return cur_hidden, alpha
+
+
+class AttentionLSTM(nn.Layer):
+    def __init__(self, in_channels, out_channels, hidden_size, **kwargs):
+        super(AttentionLSTM, self).__init__()
+        self.input_size = in_channels
+        self.hidden_size = hidden_size
+        self.num_classes = out_channels
+
+        self.attention_cell = AttentionLSTMCell(
+            in_channels, hidden_size, out_channels, use_gru=False)
+        self.generator = nn.Linear(hidden_size, out_channels)
+
+    def _char_to_onehot(self, input_char, onehot_dim):
+        input_ont_hot = F.one_hot(input_char, onehot_dim)
+        return input_ont_hot
+
+    def forward(self, inputs, targets=None, batch_max_length=25):
+        batch_size = inputs.shape[0]
+        num_steps = batch_max_length
+
+        hidden = (paddle.zeros((batch_size, self.hidden_size)), paddle.zeros(
+            (batch_size, self.hidden_size)))
+        output_hiddens = []
+
+        if targets is not None:
+            for i in range(num_steps):
+                # one-hot vectors for a i-th char
+                char_onehots = self._char_to_onehot(
+                    targets[:, i], onehot_dim=self.num_classes)
+                hidden, alpha = self.attention_cell(hidden, inputs,
+                                                    char_onehots)
+
+                hidden = (hidden[1][0], hidden[1][1])
+                output_hiddens.append(paddle.unsqueeze(hidden[0], axis=1))
+            output = paddle.concat(output_hiddens, axis=1)
+            probs = self.generator(output)
+
+        else:
+            targets = paddle.zeros(shape=[batch_size], dtype="int32")
+            probs = None
+
+            for i in range(num_steps):
+                char_onehots = self._char_to_onehot(
+                    targets, onehot_dim=self.num_classes)
+                hidden, alpha = self.attention_cell(hidden, inputs,
+                                                    char_onehots)
+                probs_step = self.generator(hidden[0])
+                hidden = (hidden[1][0], hidden[1][1])
+                if probs is None:
+                    probs = paddle.unsqueeze(probs_step, axis=1)
+                else:
+                    probs = paddle.concat(
+                        [probs, paddle.unsqueeze(
+                            probs_step, axis=1)], axis=1)
+
+                next_input = probs_step.argmax(axis=1)
+
+                targets = next_input
+
+        return probs
+
+
+class AttentionLSTMCell(nn.Layer):
+    def __init__(self, input_size, hidden_size, num_embeddings, use_gru=False):
+        super(AttentionLSTMCell, self).__init__()
+        self.i2h = nn.Linear(input_size, hidden_size, bias_attr=False)
+        self.h2h = nn.Linear(hidden_size, hidden_size)
+        self.score = nn.Linear(hidden_size, 1, bias_attr=False)
+        if not use_gru:
+            self.rnn = nn.LSTMCell(
+                input_size=input_size + num_embeddings, hidden_size=hidden_size)
+        else:
+            self.rnn = nn.GRUCell(
+                input_size=input_size + num_embeddings, hidden_size=hidden_size)
+
+        self.hidden_size = hidden_size
+
+    def forward(self, prev_hidden, batch_H, char_onehots):
+        batch_H_proj = self.i2h(batch_H)
+        prev_hidden_proj = paddle.unsqueeze(self.h2h(prev_hidden[0]), axis=1)
+        res = paddle.add(batch_H_proj, prev_hidden_proj)
+        res = paddle.tanh(res)
+        e = self.score(res)
+
+        alpha = F.softmax(e, axis=1)
+        alpha = paddle.transpose(alpha, [0, 2, 1])
+        context = paddle.squeeze(paddle.mm(alpha, batch_H), axis=1)
+        concat_context = paddle.concat([context, char_onehots], 1)
+        cur_hidden = self.rnn(concat_context, prev_hidden)
+
+        return cur_hidden, alpha

ppocr/modeling/heads/rec_ctc_head.py

+# copyright (c) 2019 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import math
+
+import paddle
+from paddle import ParamAttr, nn
+from paddle.nn import functional as F
+
+
+def get_para_bias_attr(l2_decay, k):
+    regularizer = paddle.regularizer.L2Decay(l2_decay)
+    stdv = 1.0 / math.sqrt(k * 1.0)
+    initializer = nn.initializer.Uniform(-stdv, stdv)
+    weight_attr = ParamAttr(regularizer=regularizer, initializer=initializer)
+    bias_attr = ParamAttr(regularizer=regularizer, initializer=initializer)
+    return [weight_attr, bias_attr]
+
+
+class CTCHead(nn.Layer):
+    def __init__(self,
+                 in_channels,
+                 out_channels,
+                 fc_decay=0.0004,
+                 mid_channels=None,
+                 return_feats=False,
+                 **kwargs):
+        super(CTCHead, self).__init__()
+        if mid_channels is None:
+            weight_attr, bias_attr = get_para_bias_attr(
+                l2_decay=fc_decay, k=in_channels)
+            self.fc = nn.Linear(
+                in_channels,
+                out_channels,
+                weight_attr=weight_attr,
+                bias_attr=bias_attr)
+        else:
+            weight_attr1, bias_attr1 = get_para_bias_attr(
+                l2_decay=fc_decay, k=in_channels)
+            self.fc1 = nn.Linear(
+                in_channels,
+                mid_channels,
+                weight_attr=weight_attr1,
+                bias_attr=bias_attr1)
+
+            weight_attr2, bias_attr2 = get_para_bias_attr(
+                l2_decay=fc_decay, k=mid_channels)
+            self.fc2 = nn.Linear(
+                mid_channels,
+                out_channels,
+                weight_attr=weight_attr2,
+                bias_attr=bias_attr2)
+        self.out_channels = out_channels
+        self.mid_channels = mid_channels
+        self.return_feats = return_feats
+
+    def forward(self, x, targets=None):
+        if self.mid_channels is None:
+            predicts = self.fc(x)
+        else:
+            x = self.fc1(x)
+            predicts = self.fc2(x)
+
+        if self.return_feats:
+            result = (x, predicts)
+        else:
+            result = predicts
+        if not self.training:
+            predicts = F.softmax(predicts, axis=2)
+            result = predicts
+
+        return result

ppocr/modeling/heads/rec_multi_head.py

+# copyright (c) 2022 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License. 
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import math
+import paddle
+from paddle import ParamAttr
+import paddle.nn as nn
+import paddle.nn.functional as F
+
+from ppocr.modeling.necks.rnn import Im2Seq, EncoderWithRNN, EncoderWithFC, SequenceEncoder, EncoderWithSVTR
+from .rec_ctc_head import CTCHead
+from .rec_sar_head import SARHead
+
+
+class MultiHead(nn.Layer):
+    def __init__(self, in_channels, out_channels_list, **kwargs):
+        super().__init__()
+        self.head_list = kwargs.pop('head_list')
+        self.gtc_head = 'sar'
+        assert len(self.head_list) >= 2
+        for idx, head_name in enumerate(self.head_list):
+            name = list(head_name)[0]
+            if name == 'SARHead':
+                # sar head
+                sar_args = self.head_list[idx][name]
+                self.sar_head = eval(name)(in_channels=in_channels, \
+                    out_channels=out_channels_list['SARLabelDecode'], **sar_args)
+            elif name == 'CTCHead':
+                # ctc neck
+                self.encoder_reshape = Im2Seq(in_channels)
+                neck_args = self.head_list[idx][name]['Neck']
+                encoder_type = neck_args.pop('name')
+                self.encoder = encoder_type
+                self.ctc_encoder = SequenceEncoder(in_channels=in_channels, \
+                    encoder_type=encoder_type, **neck_args)
+                # ctc head
+                head_args = self.head_list[idx][name]['Head']
+                self.ctc_head = eval(name)(in_channels=self.ctc_encoder.out_channels, \
+                    out_channels=out_channels_list['CTCLabelDecode'], **head_args)
+            else:
+                raise NotImplementedError(
+                    '{} is not supported in MultiHead yet'.format(name))
+
+    def forward(self, x, targets=None):
+        ctc_encoder = self.ctc_encoder(x)
+        ctc_out = self.ctc_head(ctc_encoder, targets)
+        head_out = dict()
+        head_out['ctc'] = ctc_out
+        head_out['ctc_neck'] = ctc_encoder
+        # eval mode
+        if not self.training:
+            return ctc_out
+        if self.gtc_head == 'sar':
+            sar_out = self.sar_head(x, targets[1:])
+            head_out['sar'] = sar_out
+            return head_out
+        else:
+            return head_out

ppocr/modeling/heads/rec_nrtr_head.py

+# copyright (c) 2021 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import math
+import paddle
+import copy
+from paddle import nn
+import paddle.nn.functional as F
+from paddle.nn import LayerList
+from paddle.nn.initializer import XavierNormal as xavier_uniform_
+from paddle.nn import Dropout, Linear, LayerNorm, Conv2D
+import numpy as np
+from ppocr.modeling.heads.multiheadAttention import MultiheadAttention
+from paddle.nn.initializer import Constant as constant_
+from paddle.nn.initializer import XavierNormal as xavier_normal_
+
+zeros_ = constant_(value=0.)
+ones_ = constant_(value=1.)
+
+
+class Transformer(nn.Layer):
+    """A transformer model. User is able to modify the attributes as needed. The architechture
+    is based on the paper "Attention Is All You Need". Ashish Vaswani, Noam Shazeer,
+    Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez, Lukasz Kaiser, and
+    Illia Polosukhin. 2017. Attention is all you need. In Advances in Neural Information
+    Processing Systems, pages 6000-6010.
+
+    Args:
+        d_model: the number of expected features in the encoder/decoder inputs (default=512).
+        nhead: the number of heads in the multiheadattention models (default=8).
+        num_encoder_layers: the number of sub-encoder-layers in the encoder (default=6).
+        num_decoder_layers: the number of sub-decoder-layers in the decoder (default=6).
+        dim_feedforward: the dimension of the feedforward network model (default=2048).
+        dropout: the dropout value (default=0.1).
+        custom_encoder: custom encoder (default=None).
+        custom_decoder: custom decoder (default=None).
+
+    """
+
+    def __init__(self,
+                 d_model=512,
+                 nhead=8,
+                 num_encoder_layers=6,
+                 beam_size=0,
+                 num_decoder_layers=6,
+                 dim_feedforward=1024,
+                 attention_dropout_rate=0.0,
+                 residual_dropout_rate=0.1,
+                 custom_encoder=None,
+                 custom_decoder=None,
+                 in_channels=0,
+                 out_channels=0,
+                 scale_embedding=True):
+        super(Transformer, self).__init__()
+        self.out_channels = out_channels + 1
+        self.embedding = Embeddings(
+            d_model=d_model,
+            vocab=self.out_channels,
+            padding_idx=0,
+            scale_embedding=scale_embedding)
+        self.positional_encoding = PositionalEncoding(
+            dropout=residual_dropout_rate,
+            dim=d_model, )
+        if custom_encoder is not None:
+            self.encoder = custom_encoder
+        else:
+            if num_encoder_layers > 0:
+                encoder_layer = TransformerEncoderLayer(
+                    d_model, nhead, dim_feedforward, attention_dropout_rate,
+                    residual_dropout_rate)
+                self.encoder = TransformerEncoder(encoder_layer,
+                                                  num_encoder_layers)
+            else:
+                self.encoder = None
+
+        if custom_decoder is not None:
+            self.decoder = custom_decoder
+        else:
+            decoder_layer = TransformerDecoderLayer(
+                d_model, nhead, dim_feedforward, attention_dropout_rate,
+                residual_dropout_rate)
+            self.decoder = TransformerDecoder(decoder_layer, num_decoder_layers)
+
+        self._reset_parameters()
+        self.beam_size = beam_size
+        self.d_model = d_model
+        self.nhead = nhead
+        self.tgt_word_prj = nn.Linear(
+            d_model, self.out_channels, bias_attr=False)
+        w0 = np.random.normal(0.0, d_model**-0.5,
+                              (d_model, self.out_channels)).astype(np.float32)
+        self.tgt_word_prj.weight.set_value(w0)
+        self.apply(self._init_weights)
+
+    def _init_weights(self, m):
+
+        if isinstance(m, nn.Conv2D):
+            xavier_normal_(m.weight)
+            if m.bias is not None:
+                zeros_(m.bias)
+
+    def forward_train(self, src, tgt):
+        tgt = tgt[:, :-1]
+
+        tgt_key_padding_mask = self.generate_padding_mask(tgt)
+        tgt = self.embedding(tgt).transpose([1, 0, 2])
+        tgt = self.positional_encoding(tgt)
+        tgt_mask = self.generate_square_subsequent_mask(tgt.shape[0])
+
+        if self.encoder is not None:
+            src = self.positional_encoding(src.transpose([1, 0, 2]))
+            memory = self.encoder(src)
+        else:
+            memory = src.squeeze(2).transpose([2, 0, 1])
+        output = self.decoder(
+            tgt,
+            memory,
+            tgt_mask=tgt_mask,
+            memory_mask=None,
+            tgt_key_padding_mask=tgt_key_padding_mask,
+            memory_key_padding_mask=None)
+        output = output.transpose([1, 0, 2])
+        logit = self.tgt_word_prj(output)
+        return logit
+
+    def forward(self, src, targets=None):
+        """Take in and process masked source/target sequences.
+        Args:
+            src: the sequence to the encoder (required).
+            tgt: the sequence to the decoder (required).
+        Shape:
+            - src: :math:`(S, N, E)`.
+            - tgt: :math:`(T, N, E)`.
+        Examples:
+            >>> output = transformer_model(src, tgt)
+        """
+
+        if self.training:
+            max_len = targets[1].max()
+            tgt = targets[0][:, :2 + max_len]
+            return self.forward_train(src, tgt)
+        else:
+            if self.beam_size > 0:
+                return self.forward_beam(src)
+            else:
+                return self.forward_test(src)
+
+    def forward_test(self, src):
+        bs = paddle.shape(src)[0]
+        if self.encoder is not None:
+            src = self.positional_encoding(paddle.transpose(src, [1, 0, 2]))
+            memory = self.encoder(src)
+        else:
+            memory = paddle.transpose(paddle.squeeze(src, 2), [2, 0, 1])
+        dec_seq = paddle.full((bs, 1), 2, dtype=paddle.int64)
+        dec_prob = paddle.full((bs, 1), 1., dtype=paddle.float32)
+        for len_dec_seq in range(1, 25):
+            dec_seq_embed = paddle.transpose(self.embedding(dec_seq), [1, 0, 2])
+            dec_seq_embed = self.positional_encoding(dec_seq_embed)
+            tgt_mask = self.generate_square_subsequent_mask(
+                paddle.shape(dec_seq_embed)[0])
+            output = self.decoder(
+                dec_seq_embed,
+                memory,
+                tgt_mask=tgt_mask,
+                memory_mask=None,
+                tgt_key_padding_mask=None,
+                memory_key_padding_mask=None)
+            dec_output = paddle.transpose(output, [1, 0, 2])
+            dec_output = dec_output[:, -1, :]
+            word_prob = F.softmax(self.tgt_word_prj(dec_output), axis=1)
+            preds_idx = paddle.argmax(word_prob, axis=1)
+            if paddle.equal_all(
+                    preds_idx,
+                    paddle.full(
+                        paddle.shape(preds_idx), 3, dtype='int64')):
+                break
+            preds_prob = paddle.max(word_prob, axis=1)
+            dec_seq = paddle.concat(
+                [dec_seq, paddle.reshape(preds_idx, [-1, 1])], axis=1)
+            dec_prob = paddle.concat(
+                [dec_prob, paddle.reshape(preds_prob, [-1, 1])], axis=1)
+        return [dec_seq, dec_prob]
+
+    def forward_beam(self, images):
+        ''' Translation work in one batch '''
+
+        def get_inst_idx_to_tensor_position_map(inst_idx_list):
+            ''' Indicate the position of an instance in a tensor. '''
+            return {
+                inst_idx: tensor_position
+                for tensor_position, inst_idx in enumerate(inst_idx_list)
+            }
+
+        def collect_active_part(beamed_tensor, curr_active_inst_idx,
+                                n_prev_active_inst, n_bm):
+            ''' Collect tensor parts associated to active instances. '''
+
+            beamed_tensor_shape = paddle.shape(beamed_tensor)
+            n_curr_active_inst = len(curr_active_inst_idx)
+            new_shape = (n_curr_active_inst * n_bm, beamed_tensor_shape[1],
+                         beamed_tensor_shape[2])
+
+            beamed_tensor = beamed_tensor.reshape([n_prev_active_inst, -1])
+            beamed_tensor = beamed_tensor.index_select(
+                curr_active_inst_idx, axis=0)
+            beamed_tensor = beamed_tensor.reshape(new_shape)
+
+            return beamed_tensor
+
+        def collate_active_info(src_enc, inst_idx_to_position_map,
+                                active_inst_idx_list):
+            # Sentences which are still active are collected,
+            # so the decoder will not run on completed sentences.
+
+            n_prev_active_inst = len(inst_idx_to_position_map)
+            active_inst_idx = [
+                inst_idx_to_position_map[k] for k in active_inst_idx_list
+            ]
+            active_inst_idx = paddle.to_tensor(active_inst_idx, dtype='int64')
+            active_src_enc = collect_active_part(
+                src_enc.transpose([1, 0, 2]), active_inst_idx,
+                n_prev_active_inst, n_bm).transpose([1, 0, 2])
+            active_inst_idx_to_position_map = get_inst_idx_to_tensor_position_map(
+                active_inst_idx_list)
+            return active_src_enc, active_inst_idx_to_position_map
+
+        def beam_decode_step(inst_dec_beams, len_dec_seq, enc_output,
+                             inst_idx_to_position_map, n_bm,
+                             memory_key_padding_mask):
+            ''' Decode and update beam status, and then return active beam idx '''
+
+            def prepare_beam_dec_seq(inst_dec_beams, len_dec_seq):
+                dec_partial_seq = [
+                    b.get_current_state() for b in inst_dec_beams if not b.done
+                ]
+                dec_partial_seq = paddle.stack(dec_partial_seq)
+                dec_partial_seq = dec_partial_seq.reshape([-1, len_dec_seq])
+                return dec_partial_seq
+
+            def predict_word(dec_seq, enc_output, n_active_inst, n_bm,
+                             memory_key_padding_mask):
+                dec_seq = paddle.transpose(self.embedding(dec_seq), [1, 0, 2])
+                dec_seq = self.positional_encoding(dec_seq)
+                tgt_mask = self.generate_square_subsequent_mask(
+                    paddle.shape(dec_seq)[0])
+                dec_output = self.decoder(
+                    dec_seq,
+                    enc_output,
+                    tgt_mask=tgt_mask,
+                    tgt_key_padding_mask=None,
+                    memory_key_padding_mask=memory_key_padding_mask, )
+                dec_output = paddle.transpose(dec_output, [1, 0, 2])
+                dec_output = dec_output[:,
+                                        -1, :]  # Pick the last step: (bh * bm) * d_h
+                word_prob = F.softmax(self.tgt_word_prj(dec_output), axis=1)
+                word_prob = paddle.reshape(word_prob, [n_active_inst, n_bm, -1])
+                return word_prob
+
+            def collect_active_inst_idx_list(inst_beams, word_prob,
+                                             inst_idx_to_position_map):
+                active_inst_idx_list = []
+                for inst_idx, inst_position in inst_idx_to_position_map.items():
+                    is_inst_complete = inst_beams[inst_idx].advance(word_prob[
+                        inst_position])
+                    if not is_inst_complete:
+                        active_inst_idx_list += [inst_idx]
+
+                return active_inst_idx_list
+
+            n_active_inst = len(inst_idx_to_position_map)
+            dec_seq = prepare_beam_dec_seq(inst_dec_beams, len_dec_seq)
+            word_prob = predict_word(dec_seq, enc_output, n_active_inst, n_bm,
+                                     None)
+            # Update the beam with predicted word prob information and collect incomplete instances
+            active_inst_idx_list = collect_active_inst_idx_list(
+                inst_dec_beams, word_prob, inst_idx_to_position_map)
+            return active_inst_idx_list
+
+        def collect_hypothesis_and_scores(inst_dec_beams, n_best):
+            all_hyp, all_scores = [], []
+            for inst_idx in range(len(inst_dec_beams)):
+                scores, tail_idxs = inst_dec_beams[inst_idx].sort_scores()
+                all_scores += [scores[:n_best]]
+                hyps = [
+                    inst_dec_beams[inst_idx].get_hypothesis(i)
+                    for i in tail_idxs[:n_best]
+                ]
+                all_hyp += [hyps]
+            return all_hyp, all_scores
+
+        with paddle.no_grad():
+            #-- Encode
+            if self.encoder is not None:
+                src = self.positional_encoding(images.transpose([1, 0, 2]))
+                src_enc = self.encoder(src)
+            else:
+                src_enc = images.squeeze(2).transpose([0, 2, 1])
+
+            n_bm = self.beam_size
+            src_shape = paddle.shape(src_enc)
+            inst_dec_beams = [Beam(n_bm) for _ in range(1)]
+            active_inst_idx_list = list(range(1))
+            # Repeat data for beam search
+            src_enc = paddle.tile(src_enc, [1, n_bm, 1])
+            inst_idx_to_position_map = get_inst_idx_to_tensor_position_map(
+                active_inst_idx_list)
+            # Decode
+            for len_dec_seq in range(1, 25):
+                src_enc_copy = src_enc.clone()
+                active_inst_idx_list = beam_decode_step(
+                    inst_dec_beams, len_dec_seq, src_enc_copy,
+                    inst_idx_to_position_map, n_bm, None)
+                if not active_inst_idx_list:
+                    break  # all instances have finished their path to <EOS>
+                src_enc, inst_idx_to_position_map = collate_active_info(
+                    src_enc_copy, inst_idx_to_position_map,
+                    active_inst_idx_list)
+        batch_hyp, batch_scores = collect_hypothesis_and_scores(inst_dec_beams,
+                                                                1)
+        result_hyp = []
+        hyp_scores = []
+        for bs_hyp, score in zip(batch_hyp, batch_scores):
+            l = len(bs_hyp[0])
+            bs_hyp_pad = bs_hyp[0] + [3] * (25 - l)
+            result_hyp.append(bs_hyp_pad)
+            score = float(score) / l
+            hyp_score = [score for _ in range(25)]
+            hyp_scores.append(hyp_score)
+        return [
+            paddle.to_tensor(
+                np.array(result_hyp), dtype=paddle.int64),
+            paddle.to_tensor(hyp_scores)
+        ]
+
+    def generate_square_subsequent_mask(self, sz):
+        """Generate a square mask for the sequence. The masked positions are filled with float('-inf').
+            Unmasked positions are filled with float(0.0).
+        """
+        mask = paddle.zeros([sz, sz], dtype='float32')
+        mask_inf = paddle.triu(
+            paddle.full(
+                shape=[sz, sz], dtype='float32', fill_value='-inf'),
+            diagonal=1)
+        mask = mask + mask_inf
+        return mask
+
+    def generate_padding_mask(self, x):
+        padding_mask = paddle.equal(x, paddle.to_tensor(0, dtype=x.dtype))
+        return padding_mask
+
+    def _reset_parameters(self):
+        """Initiate parameters in the transformer model."""
+
+        for p in self.parameters():
+            if p.dim() > 1:
+                xavier_uniform_(p)
+
+
+class TransformerEncoder(nn.Layer):
+    """TransformerEncoder is a stack of N encoder layers
+    Args:
+        encoder_layer: an instance of the TransformerEncoderLayer() class (required).
+        num_layers: the number of sub-encoder-layers in the encoder (required).
+        norm: the layer normalization component (optional).
+    """
+
+    def __init__(self, encoder_layer, num_layers):
+        super(TransformerEncoder, self).__init__()
+        self.layers = _get_clones(encoder_layer, num_layers)
+        self.num_layers = num_layers
+
+    def forward(self, src):
+        """Pass the input through the endocder layers in turn.
+        Args:
+            src: the sequnce to the encoder (required).
+            mask: the mask for the src sequence (optional).
+            src_key_padding_mask: the mask for the src keys per batch (optional).
+        """
+        output = src
+
+        for i in range(self.num_layers):
+            output = self.layers[i](output,
+                                    src_mask=None,
+                                    src_key_padding_mask=None)
+
+        return output
+
+
+class TransformerDecoder(nn.Layer):
+    """TransformerDecoder is a stack of N decoder layers
+
+    Args:
+        decoder_layer: an instance of the TransformerDecoderLayer() class (required).
+        num_layers: the number of sub-decoder-layers in the decoder (required).
+        norm: the layer normalization component (optional).
+
+    """
+
+    def __init__(self, decoder_layer, num_layers):
+        super(TransformerDecoder, self).__init__()
+        self.layers = _get_clones(decoder_layer, num_layers)
+        self.num_layers = num_layers
+
+    def forward(self,
+                tgt,
+                memory,
+                tgt_mask=None,
+                memory_mask=None,
+                tgt_key_padding_mask=None,
+                memory_key_padding_mask=None):
+        """Pass the inputs (and mask) through the decoder layer in turn.
+
+        Args:
+            tgt: the sequence to the decoder (required).
+            memory: the sequnce from the last layer of the encoder (required).
+            tgt_mask: the mask for the tgt sequence (optional).
+            memory_mask: the mask for the memory sequence (optional).
+            tgt_key_padding_mask: the mask for the tgt keys per batch (optional).
+            memory_key_padding_mask: the mask for the memory keys per batch (optional).
+        """
+        output = tgt
+        for i in range(self.num_layers):
+            output = self.layers[i](
+                output,
+                memory,
+                tgt_mask=tgt_mask,
+                memory_mask=memory_mask,
+                tgt_key_padding_mask=tgt_key_padding_mask,
+                memory_key_padding_mask=memory_key_padding_mask)
+
+        return output
+
+
+class TransformerEncoderLayer(nn.Layer):
+    """TransformerEncoderLayer is made up of self-attn and feedforward network.
+    This standard encoder layer is based on the paper "Attention Is All You Need".
+    Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez,
+    Lukasz Kaiser, and Illia Polosukhin. 2017. Attention is all you need. In Advances in
+    Neural Information Processing Systems, pages 6000-6010. Users may modify or implement
+    in a different way during application.
+
+    Args:
+        d_model: the number of expected features in the input (required).
+        nhead: the number of heads in the multiheadattention models (required).
+        dim_feedforward: the dimension of the feedforward network model (default=2048).
+        dropout: the dropout value (default=0.1).
+
+    """
+
+    def __init__(self,
+                 d_model,
+                 nhead,
+                 dim_feedforward=2048,
+                 attention_dropout_rate=0.0,
+                 residual_dropout_rate=0.1):
+        super(TransformerEncoderLayer, self).__init__()
+        self.self_attn = MultiheadAttention(
+            d_model, nhead, dropout=attention_dropout_rate)
+
+        self.conv1 = Conv2D(
+            in_channels=d_model,
+            out_channels=dim_feedforward,
+            kernel_size=(1, 1))
+        self.conv2 = Conv2D(
+            in_channels=dim_feedforward,
+            out_channels=d_model,
+            kernel_size=(1, 1))
+
+        self.norm1 = LayerNorm(d_model)
+        self.norm2 = LayerNorm(d_model)
+        self.dropout1 = Dropout(residual_dropout_rate)
+        self.dropout2 = Dropout(residual_dropout_rate)
+
+    def forward(self, src, src_mask=None, src_key_padding_mask=None):
+        """Pass the input through the endocder layer.
+        Args:
+            src: the sequnce to the encoder layer (required).
+            src_mask: the mask for the src sequence (optional).
+            src_key_padding_mask: the mask for the src keys per batch (optional).
+        """
+        src2 = self.self_attn(
+            src,
+            src,
+            src,
+            attn_mask=src_mask,
+            key_padding_mask=src_key_padding_mask)
+        src = src + self.dropout1(src2)
+        src = self.norm1(src)
+
+        src = paddle.transpose(src, [1, 2, 0])
+        src = paddle.unsqueeze(src, 2)
+        src2 = self.conv2(F.relu(self.conv1(src)))
+        src2 = paddle.squeeze(src2, 2)
+        src2 = paddle.transpose(src2, [2, 0, 1])
+        src = paddle.squeeze(src, 2)
+        src = paddle.transpose(src, [2, 0, 1])
+
+        src = src + self.dropout2(src2)
+        src = self.norm2(src)
+        return src
+
+
+class TransformerDecoderLayer(nn.Layer):
+    """TransformerDecoderLayer is made up of self-attn, multi-head-attn and feedforward network.
+    This standard decoder layer is based on the paper "Attention Is All You Need".
+    Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez,
+    Lukasz Kaiser, and Illia Polosukhin. 2017. Attention is all you need. In Advances in
+    Neural Information Processing Systems, pages 6000-6010. Users may modify or implement
+    in a different way during application.
+
+    Args:
+        d_model: the number of expected features in the input (required).
+        nhead: the number of heads in the multiheadattention models (required).
+        dim_feedforward: the dimension of the feedforward network model (default=2048).
+        dropout: the dropout value (default=0.1).
+
+    """
+
+    def __init__(self,
+                 d_model,
+                 nhead,
+                 dim_feedforward=2048,
+                 attention_dropout_rate=0.0,
+                 residual_dropout_rate=0.1):
+        super(TransformerDecoderLayer, self).__init__()
+        self.self_attn = MultiheadAttention(
+            d_model, nhead, dropout=attention_dropout_rate)
+        self.multihead_attn = MultiheadAttention(
+            d_model, nhead, dropout=attention_dropout_rate)
+
+        self.conv1 = Conv2D(
+            in_channels=d_model,
+            out_channels=dim_feedforward,
+            kernel_size=(1, 1))
+        self.conv2 = Conv2D(
+            in_channels=dim_feedforward,
+            out_channels=d_model,
+            kernel_size=(1, 1))
+
+        self.norm1 = LayerNorm(d_model)
+        self.norm2 = LayerNorm(d_model)
+        self.norm3 = LayerNorm(d_model)
+        self.dropout1 = Dropout(residual_dropout_rate)
+        self.dropout2 = Dropout(residual_dropout_rate)
+        self.dropout3 = Dropout(residual_dropout_rate)
+
+    def forward(self,
+                tgt,
+                memory,
+                tgt_mask=None,
+                memory_mask=None,
+                tgt_key_padding_mask=None,
+                memory_key_padding_mask=None):
+        """Pass the inputs (and mask) through the decoder layer.
+
+        Args:
+            tgt: the sequence to the decoder layer (required).
+            memory: the sequnce from the last layer of the encoder (required).
+            tgt_mask: the mask for the tgt sequence (optional).
+            memory_mask: the mask for the memory sequence (optional).
+            tgt_key_padding_mask: the mask for the tgt keys per batch (optional).
+            memory_key_padding_mask: the mask for the memory keys per batch (optional).
+
+        """
+        tgt2 = self.self_attn(
+            tgt,
+            tgt,
+            tgt,
+            attn_mask=tgt_mask,
+            key_padding_mask=tgt_key_padding_mask)
+        tgt = tgt + self.dropout1(tgt2)
+        tgt = self.norm1(tgt)
+        tgt2 = self.multihead_attn(
+            tgt,
+            memory,
+            memory,
+            attn_mask=memory_mask,
+            key_padding_mask=memory_key_padding_mask)
+        tgt = tgt + self.dropout2(tgt2)
+        tgt = self.norm2(tgt)
+
+        # default
+        tgt = paddle.transpose(tgt, [1, 2, 0])
+        tgt = paddle.unsqueeze(tgt, 2)
+        tgt2 = self.conv2(F.relu(self.conv1(tgt)))
+        tgt2 = paddle.squeeze(tgt2, 2)
+        tgt2 = paddle.transpose(tgt2, [2, 0, 1])
+        tgt = paddle.squeeze(tgt, 2)
+        tgt = paddle.transpose(tgt, [2, 0, 1])
+
+        tgt = tgt + self.dropout3(tgt2)
+        tgt = self.norm3(tgt)
+        return tgt
+
+
+def _get_clones(module, N):
+    return LayerList([copy.deepcopy(module) for i in range(N)])
+
+
+class PositionalEncoding(nn.Layer):
+    """Inject some information about the relative or absolute position of the tokens
+        in the sequence. The positional encodings have the same dimension as
+        the embeddings, so that the two can be summed. Here, we use sine and cosine
+        functions of different frequencies.
+    .. math::
+        \text{PosEncoder}(pos, 2i) = sin(pos/10000^(2i/d_model))
+        \text{PosEncoder}(pos, 2i+1) = cos(pos/10000^(2i/d_model))
+        \text{where pos is the word position and i is the embed idx)
+    Args:
+        d_model: the embed dim (required).
+        dropout: the dropout value (default=0.1).
+        max_len: the max. length of the incoming sequence (default=5000).
+    Examples:
+        >>> pos_encoder = PositionalEncoding(d_model)
+    """
+
+    def __init__(self, dropout, dim, max_len=5000):
+        super(PositionalEncoding, self).__init__()
+        self.dropout = nn.Dropout(p=dropout)
+
+        pe = paddle.zeros([max_len, dim])
+        position = paddle.arange(0, max_len, dtype=paddle.float32).unsqueeze(1)
+        div_term = paddle.exp(
+            paddle.arange(0, dim, 2).astype('float32') *
+            (-math.log(10000.0) / dim))
+        pe[:, 0::2] = paddle.sin(position * div_term)
+        pe[:, 1::2] = paddle.cos(position * div_term)
+        pe = paddle.unsqueeze(pe, 0)
+        pe = paddle.transpose(pe, [1, 0, 2])
+        self.register_buffer('pe', pe)
+
+    def forward(self, x):
+        """Inputs of forward function
+        Args:
+            x: the sequence fed to the positional encoder model (required).
+        Shape:
+            x: [sequence length, batch size, embed dim]
+            output: [sequence length, batch size, embed dim]
+        Examples:
+            >>> output = pos_encoder(x)
+        """
+        x = x + self.pe[:paddle.shape(x)[0], :]
+        return self.dropout(x)
+
+
+class PositionalEncoding_2d(nn.Layer):
+    """Inject some information about the relative or absolute position of the tokens
+        in the sequence. The positional encodings have the same dimension as
+        the embeddings, so that the two can be summed. Here, we use sine and cosine
+        functions of different frequencies.
+    .. math::
+        \text{PosEncoder}(pos, 2i) = sin(pos/10000^(2i/d_model))
+        \text{PosEncoder}(pos, 2i+1) = cos(pos/10000^(2i/d_model))
+        \text{where pos is the word position and i is the embed idx)
+    Args:
+        d_model: the embed dim (required).
+        dropout: the dropout value (default=0.1).
+        max_len: the max. length of the incoming sequence (default=5000).
+    Examples:
+        >>> pos_encoder = PositionalEncoding(d_model)
+    """
+
+    def __init__(self, dropout, dim, max_len=5000):
+        super(PositionalEncoding_2d, self).__init__()
+        self.dropout = nn.Dropout(p=dropout)
+
+        pe = paddle.zeros([max_len, dim])
+        position = paddle.arange(0, max_len, dtype=paddle.float32).unsqueeze(1)
+        div_term = paddle.exp(
+            paddle.arange(0, dim, 2).astype('float32') *
+            (-math.log(10000.0) / dim))
+        pe[:, 0::2] = paddle.sin(position * div_term)
+        pe[:, 1::2] = paddle.cos(position * div_term)
+        pe = paddle.transpose(paddle.unsqueeze(pe, 0), [1, 0, 2])
+        self.register_buffer('pe', pe)
+
+        self.avg_pool_1 = nn.AdaptiveAvgPool2D((1, 1))
+        self.linear1 = nn.Linear(dim, dim)
+        self.linear1.weight.data.fill_(1.)
+        self.avg_pool_2 = nn.AdaptiveAvgPool2D((1, 1))
+        self.linear2 = nn.Linear(dim, dim)
+        self.linear2.weight.data.fill_(1.)
+
+    def forward(self, x):
+        """Inputs of forward function
+        Args:
+            x: the sequence fed to the positional encoder model (required).
+        Shape:
+            x: [sequence length, batch size, embed dim]
+            output: [sequence length, batch size, embed dim]
+        Examples:
+            >>> output = pos_encoder(x)
+        """
+        w_pe = self.pe[:paddle.shape(x)[-1], :]
+        w1 = self.linear1(self.avg_pool_1(x).squeeze()).unsqueeze(0)
+        w_pe = w_pe * w1
+        w_pe = paddle.transpose(w_pe, [1, 2, 0])
+        w_pe = paddle.unsqueeze(w_pe, 2)
+
+        h_pe = self.pe[:paddle.shape(x).shape[-2], :]
+        w2 = self.linear2(self.avg_pool_2(x).squeeze()).unsqueeze(0)
+        h_pe = h_pe * w2
+        h_pe = paddle.transpose(h_pe, [1, 2, 0])
+        h_pe = paddle.unsqueeze(h_pe, 3)
+
+        x = x + w_pe + h_pe
+        x = paddle.transpose(
+            paddle.reshape(x,
+                           [x.shape[0], x.shape[1], x.shape[2] * x.shape[3]]),
+            [2, 0, 1])
+
+        return self.dropout(x)
+
+
+class Embeddings(nn.Layer):
+    def __init__(self, d_model, vocab, padding_idx, scale_embedding):
+        super(Embeddings, self).__init__()
+        self.embedding = nn.Embedding(vocab, d_model, padding_idx=padding_idx)
+        w0 = np.random.normal(0.0, d_model**-0.5,
+                              (vocab, d_model)).astype(np.float32)
+        self.embedding.weight.set_value(w0)
+        self.d_model = d_model
+        self.scale_embedding = scale_embedding
+
+    def forward(self, x):
+        if self.scale_embedding:
+            x = self.embedding(x)
+            return x * math.sqrt(self.d_model)
+        return self.embedding(x)
+
+
+class Beam():
+    ''' Beam search '''
+
+    def __init__(self, size, device=False):
+
+        self.size = size
+        self._done = False
+        # The score for each translation on the beam.
+        self.scores = paddle.zeros((size, ), dtype=paddle.float32)
+        self.all_scores = []
+        # The backpointers at each time-step.
+        self.prev_ks = []
+        # The outputs at each time-step.
+        self.next_ys = [paddle.full((size, ), 0, dtype=paddle.int64)]
+        self.next_ys[0][0] = 2
+
+    def get_current_state(self):
+        "Get the outputs for the current timestep."
+        return self.get_tentative_hypothesis()
+
+    def get_current_origin(self):
+        "Get the backpointers for the current timestep."
+        return self.prev_ks[-1]
+
+    @property
+    def done(self):
+        return self._done
+
+    def advance(self, word_prob):
+        "Update beam status and check if finished or not."
+        num_words = word_prob.shape[1]
+
+        # Sum the previous scores.
+        if len(self.prev_ks) > 0:
+            beam_lk = word_prob + self.scores.unsqueeze(1).expand_as(word_prob)
+        else:
+            beam_lk = word_prob[0]
+
+        flat_beam_lk = beam_lk.reshape([-1])
+        best_scores, best_scores_id = flat_beam_lk.topk(self.size, 0, True,
+                                                        True)  # 1st sort
+        self.all_scores.append(self.scores)
+        self.scores = best_scores
+        # bestScoresId is flattened as a (beam x word) array,
+        # so we need to calculate which word and beam each score came from
+        prev_k = best_scores_id // num_words
+        self.prev_ks.append(prev_k)
+        self.next_ys.append(best_scores_id - prev_k * num_words)
+        # End condition is when top-of-beam is EOS.
+        if self.next_ys[-1][0] == 3:
+            self._done = True
+            self.all_scores.append(self.scores)
+
+        return self._done
+
+    def sort_scores(self):
+        "Sort the scores."
+        return self.scores, paddle.to_tensor(
+            [i for i in range(int(self.scores.shape[0]))], dtype='int32')
+
+    def get_the_best_score_and_idx(self):
+        "Get the score of the best in the beam."
+        scores, ids = self.sort_scores()
+        return scores[1], ids[1]
+
+    def get_tentative_hypothesis(self):
+        "Get the decoded sequence for the current timestep."
+        if len(self.next_ys) == 1:
+            dec_seq = self.next_ys[0].unsqueeze(1)
+        else:
+            _, keys = self.sort_scores()
+            hyps = [self.get_hypothesis(k) for k in keys]
+            hyps = [[2] + h for h in hyps]
+            dec_seq = paddle.to_tensor(hyps, dtype='int64')
+        return dec_seq
+
+    def get_hypothesis(self, k):
+        """ Walk back to construct the full hypothesis. """
+        hyp = []
+        for j in range(len(self.prev_ks) - 1, -1, -1):
+            hyp.append(self.next_ys[j + 1][k])
+            k = self.prev_ks[j][k]
+        return list(map(lambda x: x.item(), hyp[::-1]))

ppocr/modeling/heads/rec_pren_head.py

+# copyright (c) 2022 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+from paddle import nn
+from paddle.nn import functional as F
+
+
+class PRENHead(nn.Layer):
+    def __init__(self, in_channels, out_channels, **kwargs):
+        super(PRENHead, self).__init__()
+        self.linear = nn.Linear(in_channels, out_channels)
+
+    def forward(self, x, targets=None):
+        predicts = self.linear(x)
+
+        if not self.training:
+            predicts = F.softmax(predicts, axis=2)
+
+        return predicts

ppocr/modeling/heads/rec_sar_head.py

+# copyright (c) 2021 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+This code is refer from: 
+https://github.com/open-mmlab/mmocr/blob/main/mmocr/models/textrecog/encoders/sar_encoder.py
+https://github.com/open-mmlab/mmocr/blob/main/mmocr/models/textrecog/decoders/sar_decoder.py
+"""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import math
+import paddle
+from paddle import ParamAttr
+import paddle.nn as nn
+import paddle.nn.functional as F
+
+
+class SAREncoder(nn.Layer):
+    """
+    Args:
+        enc_bi_rnn (bool): If True, use bidirectional RNN in encoder.
+        enc_drop_rnn (float): Dropout probability of RNN layer in encoder.
+        enc_gru (bool): If True, use GRU, else LSTM in encoder.
+        d_model (int): Dim of channels from backbone.
+        d_enc (int): Dim of encoder RNN layer.
+        mask (bool): If True, mask padding in RNN sequence.
+    """
+
+    def __init__(self,
+                 enc_bi_rnn=False,
+                 enc_drop_rnn=0.1,
+                 enc_gru=False,
+                 d_model=512,
+                 d_enc=512,
+                 mask=True,
+                 **kwargs):
+        super().__init__()
+        assert isinstance(enc_bi_rnn, bool)
+        assert isinstance(enc_drop_rnn, (int, float))
+        assert 0 <= enc_drop_rnn < 1.0
+        assert isinstance(enc_gru, bool)
+        assert isinstance(d_model, int)
+        assert isinstance(d_enc, int)
+        assert isinstance(mask, bool)
+
+        self.enc_bi_rnn = enc_bi_rnn
+        self.enc_drop_rnn = enc_drop_rnn
+        self.mask = mask
+
+        # LSTM Encoder
+        if enc_bi_rnn:
+            direction = 'bidirectional'
+        else:
+            direction = 'forward'
+        kwargs = dict(
+            input_size=d_model,
+            hidden_size=d_enc,
+            num_layers=2,
+            time_major=False,
+            dropout=enc_drop_rnn,
+            direction=direction)
+        if enc_gru:
+            self.rnn_encoder = nn.GRU(**kwargs)
+        else:
+            self.rnn_encoder = nn.LSTM(**kwargs)
+
+        # global feature transformation
+        encoder_rnn_out_size = d_enc * (int(enc_bi_rnn) + 1)
+        self.linear = nn.Linear(encoder_rnn_out_size, encoder_rnn_out_size)
+
+    def forward(self, feat, img_metas=None):
+        if img_metas is not None:
+            assert len(img_metas[0]) == paddle.shape(feat)[0]
+
+        valid_ratios = None
+        if img_metas is not None and self.mask:
+            valid_ratios = img_metas[-1]
+
+        h_feat = feat.shape[2]  # bsz c h w
+        feat_v = F.max_pool2d(
+            feat, kernel_size=(h_feat, 1), stride=1, padding=0)
+        feat_v = feat_v.squeeze(2)  # bsz * C * W
+        feat_v = paddle.transpose(feat_v, perm=[0, 2, 1])  # bsz * W * C
+        holistic_feat = self.rnn_encoder(feat_v)[0]  # bsz * T * C
+
+        if valid_ratios is not None:
+            valid_hf = []
+            T = paddle.shape(holistic_feat)[1]
+            for i in range(paddle.shape(valid_ratios)[0]):
+                valid_step = paddle.minimum(
+                    T, paddle.ceil(valid_ratios[i] * T).astype('int32')) - 1
+                valid_hf.append(holistic_feat[i, valid_step, :])
+            valid_hf = paddle.stack(valid_hf, axis=0)
+        else:
+            valid_hf = holistic_feat[:, -1, :]  # bsz * C
+        holistic_feat = self.linear(valid_hf)  # bsz * C
+
+        return holistic_feat
+
+
+class BaseDecoder(nn.Layer):
+    def __init__(self, **kwargs):
+        super().__init__()
+
+    def forward_train(self, feat, out_enc, targets, img_metas):
+        raise NotImplementedError
+
+    def forward_test(self, feat, out_enc, img_metas):
+        raise NotImplementedError
+
+    def forward(self,
+                feat,
+                out_enc,
+                label=None,
+                img_metas=None,
+                train_mode=True):
+        self.train_mode = train_mode
+
+        if train_mode:
+            return self.forward_train(feat, out_enc, label, img_metas)
+        return self.forward_test(feat, out_enc, img_metas)
+
+
+class ParallelSARDecoder(BaseDecoder):
+    """
+    Args:
+        out_channels (int): Output class number.
+        enc_bi_rnn (bool): If True, use bidirectional RNN in encoder.
+        dec_bi_rnn (bool): If True, use bidirectional RNN in decoder.
+        dec_drop_rnn (float): Dropout of RNN layer in decoder.
+        dec_gru (bool): If True, use GRU, else LSTM in decoder.
+        d_model (int): Dim of channels from backbone.
+        d_enc (int): Dim of encoder RNN layer.
+        d_k (int): Dim of channels of attention module.
+        pred_dropout (float): Dropout probability of prediction layer.
+        max_seq_len (int): Maximum sequence length for decoding.
+        mask (bool): If True, mask padding in feature map.
+        start_idx (int): Index of start token.
+        padding_idx (int): Index of padding token.
+        pred_concat (bool): If True, concat glimpse feature from
+            attention with holistic feature and hidden state.
+    """
+
+    def __init__(
+            self,
+            out_channels,  # 90 + unknown + start + padding
+            enc_bi_rnn=False,
+            dec_bi_rnn=False,
+            dec_drop_rnn=0.0,
+            dec_gru=False,
+            d_model=512,
+            d_enc=512,
+            d_k=64,
+            pred_dropout=0.1,
+            max_text_length=30,
+            mask=True,
+            pred_concat=True,
+            **kwargs):
+        super().__init__()
+
+        self.num_classes = out_channels
+        self.enc_bi_rnn = enc_bi_rnn
+        self.d_k = d_k
+        self.start_idx = out_channels - 2
+        self.padding_idx = out_channels - 1
+        self.max_seq_len = max_text_length
+        self.mask = mask
+        self.pred_concat = pred_concat
+
+        encoder_rnn_out_size = d_enc * (int(enc_bi_rnn) + 1)
+        decoder_rnn_out_size = encoder_rnn_out_size * (int(dec_bi_rnn) + 1)
+
+        # 2D attention layer
+        self.conv1x1_1 = nn.Linear(decoder_rnn_out_size, d_k)
+        self.conv3x3_1 = nn.Conv2D(
+            d_model, d_k, kernel_size=3, stride=1, padding=1)
+        self.conv1x1_2 = nn.Linear(d_k, 1)
+
+        # Decoder RNN layer
+        if dec_bi_rnn:
+            direction = 'bidirectional'
+        else:
+            direction = 'forward'
+
+        kwargs = dict(
+            input_size=encoder_rnn_out_size,
+            hidden_size=encoder_rnn_out_size,
+            num_layers=2,
+            time_major=False,
+            dropout=dec_drop_rnn,
+            direction=direction)
+        if dec_gru:
+            self.rnn_decoder = nn.GRU(**kwargs)
+        else:
+            self.rnn_decoder = nn.LSTM(**kwargs)
+
+        # Decoder input embedding
+        self.embedding = nn.Embedding(
+            self.num_classes,
+            encoder_rnn_out_size,
+            padding_idx=self.padding_idx)
+
+        # Prediction layer
+        self.pred_dropout = nn.Dropout(pred_dropout)
+        pred_num_classes = self.num_classes - 1
+        if pred_concat:
+            fc_in_channel = decoder_rnn_out_size + d_model + encoder_rnn_out_size
+        else:
+            fc_in_channel = d_model
+        self.prediction = nn.Linear(fc_in_channel, pred_num_classes)
+
+    def _2d_attention(self,
+                      decoder_input,
+                      feat,
+                      holistic_feat,
+                      valid_ratios=None):
+
+        y = self.rnn_decoder(decoder_input)[0]
+        # y: bsz * (seq_len + 1) * hidden_size
+
+        attn_query = self.conv1x1_1(y)  # bsz * (seq_len + 1) * attn_size
+        bsz, seq_len, attn_size = attn_query.shape
+        attn_query = paddle.unsqueeze(attn_query, axis=[3, 4])
+        # (bsz, seq_len + 1, attn_size, 1, 1)
+
+        attn_key = self.conv3x3_1(feat)
+        # bsz * attn_size * h * w
+        attn_key = attn_key.unsqueeze(1)
+        # bsz * 1 * attn_size * h * w
+
+        attn_weight = paddle.tanh(paddle.add(attn_key, attn_query))
+
+        # bsz * (seq_len + 1) * attn_size * h * w
+        attn_weight = paddle.transpose(attn_weight, perm=[0, 1, 3, 4, 2])
+        # bsz * (seq_len + 1) * h * w * attn_size
+        attn_weight = self.conv1x1_2(attn_weight)
+        # bsz * (seq_len + 1) * h * w * 1
+        bsz, T, h, w, c = paddle.shape(attn_weight)
+        assert c == 1
+
+        if valid_ratios is not None:
+            # cal mask of attention weight
+            for i in range(paddle.shape(valid_ratios)[0]):
+                valid_width = paddle.minimum(
+                    w, paddle.ceil(valid_ratios[i] * w).astype("int32"))
+                if valid_width < w:
+                    attn_weight[i, :, :, valid_width:, :] = float('-inf')
+
+        attn_weight = paddle.reshape(attn_weight, [bsz, T, -1])
+        attn_weight = F.softmax(attn_weight, axis=-1)
+
+        attn_weight = paddle.reshape(attn_weight, [bsz, T, h, w, c])
+        attn_weight = paddle.transpose(attn_weight, perm=[0, 1, 4, 2, 3])
+        # attn_weight: bsz * T * c * h * w
+        # feat: bsz * c * h * w
+        attn_feat = paddle.sum(paddle.multiply(feat.unsqueeze(1), attn_weight),
+                               (3, 4),
+                               keepdim=False)
+        # bsz * (seq_len + 1) * C
+
+        # Linear transformation
+        if self.pred_concat:
+            hf_c = holistic_feat.shape[-1]
+            holistic_feat = paddle.expand(
+                holistic_feat, shape=[bsz, seq_len, hf_c])
+            y = self.prediction(paddle.concat((y, attn_feat, holistic_feat), 2))
+        else:
+            y = self.prediction(attn_feat)
+        # bsz * (seq_len + 1) * num_classes
+        if self.train_mode:
+            y = self.pred_dropout(y)
+
+        return y
+
+    def forward_train(self, feat, out_enc, label, img_metas):
+        '''
+        img_metas: [label, valid_ratio]
+        '''
+        if img_metas is not None:
+            assert paddle.shape(img_metas[0])[0] == paddle.shape(feat)[0]
+
+        valid_ratios = None
+        if img_metas is not None and self.mask:
+            valid_ratios = img_metas[-1]
+
+        lab_embedding = self.embedding(label)
+        # bsz * seq_len * emb_dim
+        out_enc = out_enc.unsqueeze(1)
+        # bsz * 1 * emb_dim
+        in_dec = paddle.concat((out_enc, lab_embedding), axis=1)
+        # bsz * (seq_len + 1) * C
+        out_dec = self._2d_attention(
+            in_dec, feat, out_enc, valid_ratios=valid_ratios)
+
+        return out_dec[:, 1:, :]  # bsz * seq_len * num_classes
+
+    def forward_test(self, feat, out_enc, img_metas):
+        if img_metas is not None:
+            assert len(img_metas[0]) == feat.shape[0]
+
+        valid_ratios = None
+        if img_metas is not None and self.mask:
+            valid_ratios = img_metas[-1]
+
+        seq_len = self.max_seq_len
+        bsz = feat.shape[0]
+        start_token = paddle.full(
+            (bsz, ), fill_value=self.start_idx, dtype='int64')
+        # bsz
+        start_token = self.embedding(start_token)
+        # bsz * emb_dim
+        emb_dim = start_token.shape[1]
+        start_token = start_token.unsqueeze(1)
+        start_token = paddle.expand(start_token, shape=[bsz, seq_len, emb_dim])
+        # bsz * seq_len * emb_dim
+        out_enc = out_enc.unsqueeze(1)
+        # bsz * 1 * emb_dim
+        decoder_input = paddle.concat((out_enc, start_token), axis=1)
+        # bsz * (seq_len + 1) * emb_dim
+
+        outputs = []
+        for i in range(1, seq_len + 1):
+            decoder_output = self._2d_attention(
+                decoder_input, feat, out_enc, valid_ratios=valid_ratios)
+            char_output = decoder_output[:, i, :]  # bsz * num_classes
+            char_output = F.softmax(char_output, -1)
+            outputs.append(char_output)
+            max_idx = paddle.argmax(char_output, axis=1, keepdim=False)
+            char_embedding = self.embedding(max_idx)  # bsz * emb_dim
+            if i < seq_len:
+                decoder_input[:, i + 1, :] = char_embedding
+
+        outputs = paddle.stack(outputs, 1)  # bsz * seq_len * num_classes
+
+        return outputs
+
+
+class SARHead(nn.Layer):
+    def __init__(self,
+                 in_channels,
+                 out_channels,
+                 enc_dim=512,
+                 max_text_length=30,
+                 enc_bi_rnn=False,
+                 enc_drop_rnn=0.1,
+                 enc_gru=False,
+                 dec_bi_rnn=False,
+                 dec_drop_rnn=0.0,
+                 dec_gru=False,
+                 d_k=512,
+                 pred_dropout=0.1,
+                 pred_concat=True,
+                 **kwargs):
+        super(SARHead, self).__init__()
+
+        # encoder module
+        self.encoder = SAREncoder(
+            enc_bi_rnn=enc_bi_rnn,
+            enc_drop_rnn=enc_drop_rnn,
+            enc_gru=enc_gru,
+            d_model=in_channels,
+            d_enc=enc_dim)
+
+        # decoder module
+        self.decoder = ParallelSARDecoder(
+            out_channels=out_channels,
+            enc_bi_rnn=enc_bi_rnn,
+            dec_bi_rnn=dec_bi_rnn,
+            dec_drop_rnn=dec_drop_rnn,
+            dec_gru=dec_gru,
+            d_model=in_channels,
+            d_enc=enc_dim,
+            d_k=d_k,
+            pred_dropout=pred_dropout,
+            max_text_length=max_text_length,
+            pred_concat=pred_concat)
+
+    def forward(self, feat, targets=None):
+        '''
+        img_metas: [label, valid_ratio]
+        '''
+        holistic_feat = self.encoder(feat, targets)  # bsz c
+
+        if self.training:
+            label = targets[0]  # label
+            final_out = self.decoder(
+                feat, holistic_feat, label, img_metas=targets)
+        else:
+            final_out = self.decoder(
+                feat,
+                holistic_feat,
+                label=None,
+                img_metas=targets,
+                train_mode=False)
+            # (bsz, seq_len, num_classes)
+
+        return final_out

ppocr/modeling/heads/rec_srn_head.py

+# copyright (c) 2020 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import math
+import paddle
+from paddle import nn, ParamAttr
+from paddle.nn import functional as F
+import numpy as np
+from .self_attention import WrapEncoderForFeature
+from .self_attention import WrapEncoder
+from paddle.static import Program
+from ppocr.modeling.backbones.rec_resnet_fpn import ResNetFPN
+
+from collections import OrderedDict
+gradient_clip = 10
+
+
+class PVAM(nn.Layer):
+    def __init__(self, in_channels, char_num, max_text_length, num_heads,
+                 num_encoder_tus, hidden_dims):
+        super(PVAM, self).__init__()
+        self.char_num = char_num
+        self.max_length = max_text_length
+        self.num_heads = num_heads
+        self.num_encoder_TUs = num_encoder_tus
+        self.hidden_dims = hidden_dims
+        # Transformer encoder
+        t = 256
+        c = 512
+        self.wrap_encoder_for_feature = WrapEncoderForFeature(
+            src_vocab_size=1,
+            max_length=t,
+            n_layer=self.num_encoder_TUs,
+            n_head=self.num_heads,
+            d_key=int(self.hidden_dims / self.num_heads),
+            d_value=int(self.hidden_dims / self.num_heads),
+            d_model=self.hidden_dims,
+            d_inner_hid=self.hidden_dims,
+            prepostprocess_dropout=0.1,
+            attention_dropout=0.1,
+            relu_dropout=0.1,
+            preprocess_cmd="n",
+            postprocess_cmd="da",
+            weight_sharing=True)
+
+        # PVAM
+        self.flatten0 = paddle.nn.Flatten(start_axis=0, stop_axis=1)
+        self.fc0 = paddle.nn.Linear(
+            in_features=in_channels,
+            out_features=in_channels, )
+        self.emb = paddle.nn.Embedding(
+            num_embeddings=self.max_length, embedding_dim=in_channels)
+        self.flatten1 = paddle.nn.Flatten(start_axis=0, stop_axis=2)
+        self.fc1 = paddle.nn.Linear(
+            in_features=in_channels, out_features=1, bias_attr=False)
+
+    def forward(self, inputs, encoder_word_pos, gsrm_word_pos):
+        b, c, h, w = inputs.shape
+        conv_features = paddle.reshape(inputs, shape=[-1, c, h * w])
+        conv_features = paddle.transpose(conv_features, perm=[0, 2, 1])
+        # transformer encoder
+        b, t, c = conv_features.shape
+
+        enc_inputs = [conv_features, encoder_word_pos, None]
+        word_features = self.wrap_encoder_for_feature(enc_inputs)
+
+        # pvam
+        b, t, c = word_features.shape
+        word_features = self.fc0(word_features)
+        word_features_ = paddle.reshape(word_features, [-1, 1, t, c])
+        word_features_ = paddle.tile(word_features_, [1, self.max_length, 1, 1])
+        word_pos_feature = self.emb(gsrm_word_pos)
+        word_pos_feature_ = paddle.reshape(word_pos_feature,
+                                           [-1, self.max_length, 1, c])
+        word_pos_feature_ = paddle.tile(word_pos_feature_, [1, 1, t, 1])
+        y = word_pos_feature_ + word_features_
+        y = F.tanh(y)
+        attention_weight = self.fc1(y)
+        attention_weight = paddle.reshape(
+            attention_weight, shape=[-1, self.max_length, t])
+        attention_weight = F.softmax(attention_weight, axis=-1)
+        pvam_features = paddle.matmul(attention_weight,
+                                      word_features)  #[b, max_length, c]
+        return pvam_features
+
+
+class GSRM(nn.Layer):
+    def __init__(self, in_channels, char_num, max_text_length, num_heads,
+                 num_encoder_tus, num_decoder_tus, hidden_dims):
+        super(GSRM, self).__init__()
+        self.char_num = char_num
+        self.max_length = max_text_length
+        self.num_heads = num_heads
+        self.num_encoder_TUs = num_encoder_tus
+        self.num_decoder_TUs = num_decoder_tus
+        self.hidden_dims = hidden_dims
+
+        self.fc0 = paddle.nn.Linear(
+            in_features=in_channels, out_features=self.char_num)
+        self.wrap_encoder0 = WrapEncoder(
+            src_vocab_size=self.char_num + 1,
+            max_length=self.max_length,
+            n_layer=self.num_decoder_TUs,
+            n_head=self.num_heads,
+            d_key=int(self.hidden_dims / self.num_heads),
+            d_value=int(self.hidden_dims / self.num_heads),
+            d_model=self.hidden_dims,
+            d_inner_hid=self.hidden_dims,
+            prepostprocess_dropout=0.1,
+            attention_dropout=0.1,
+            relu_dropout=0.1,
+            preprocess_cmd="n",
+            postprocess_cmd="da",
+            weight_sharing=True)
+
+        self.wrap_encoder1 = WrapEncoder(
+            src_vocab_size=self.char_num + 1,
+            max_length=self.max_length,
+            n_layer=self.num_decoder_TUs,
+            n_head=self.num_heads,
+            d_key=int(self.hidden_dims / self.num_heads),
+            d_value=int(self.hidden_dims / self.num_heads),
+            d_model=self.hidden_dims,
+            d_inner_hid=self.hidden_dims,
+            prepostprocess_dropout=0.1,
+            attention_dropout=0.1,
+            relu_dropout=0.1,
+            preprocess_cmd="n",
+            postprocess_cmd="da",
+            weight_sharing=True)
+
+        self.mul = lambda x: paddle.matmul(x=x,
+                                           y=self.wrap_encoder0.prepare_decoder.emb0.weight,
+                                           transpose_y=True)
+
+    def forward(self, inputs, gsrm_word_pos, gsrm_slf_attn_bias1,
+                gsrm_slf_attn_bias2):
+        # ===== GSRM Visual-to-semantic embedding block =====
+        b, t, c = inputs.shape
+        pvam_features = paddle.reshape(inputs, [-1, c])
+        word_out = self.fc0(pvam_features)
+        word_ids = paddle.argmax(F.softmax(word_out), axis=1)
+        word_ids = paddle.reshape(x=word_ids, shape=[-1, t, 1])
+
+        #===== GSRM Semantic reasoning block =====
+        """
+        This module is achieved through bi-transformers,
+        ngram_feature1 is the froward one, ngram_fetaure2 is the backward one
+        """
+        pad_idx = self.char_num
+
+        word1 = paddle.cast(word_ids, "float32")
+        word1 = F.pad(word1, [1, 0], value=1.0 * pad_idx, data_format="NLC")
+        word1 = paddle.cast(word1, "int64")
+        word1 = word1[:, :-1, :]
+        word2 = word_ids
+
+        enc_inputs_1 = [word1, gsrm_word_pos, gsrm_slf_attn_bias1]
+        enc_inputs_2 = [word2, gsrm_word_pos, gsrm_slf_attn_bias2]
+
+        gsrm_feature1 = self.wrap_encoder0(enc_inputs_1)
+        gsrm_feature2 = self.wrap_encoder1(enc_inputs_2)
+
+        gsrm_feature2 = F.pad(gsrm_feature2, [0, 1],
+                              value=0.,
+                              data_format="NLC")
+        gsrm_feature2 = gsrm_feature2[:, 1:, ]
+        gsrm_features = gsrm_feature1 + gsrm_feature2
+
+        gsrm_out = self.mul(gsrm_features)
+
+        b, t, c = gsrm_out.shape
+        gsrm_out = paddle.reshape(gsrm_out, [-1, c])
+
+        return gsrm_features, word_out, gsrm_out
+
+
+class VSFD(nn.Layer):
+    def __init__(self, in_channels=512, pvam_ch=512, char_num=38):
+        super(VSFD, self).__init__()
+        self.char_num = char_num
+        self.fc0 = paddle.nn.Linear(
+            in_features=in_channels * 2, out_features=pvam_ch)
+        self.fc1 = paddle.nn.Linear(
+            in_features=pvam_ch, out_features=self.char_num)
+
+    def forward(self, pvam_feature, gsrm_feature):
+        b, t, c1 = pvam_feature.shape
+        b, t, c2 = gsrm_feature.shape
+        combine_feature_ = paddle.concat([pvam_feature, gsrm_feature], axis=2)
+        img_comb_feature_ = paddle.reshape(
+            combine_feature_, shape=[-1, c1 + c2])
+        img_comb_feature_map = self.fc0(img_comb_feature_)
+        img_comb_feature_map = F.sigmoid(img_comb_feature_map)
+        img_comb_feature_map = paddle.reshape(
+            img_comb_feature_map, shape=[-1, t, c1])
+        combine_feature = img_comb_feature_map * pvam_feature + (
+            1.0 - img_comb_feature_map) * gsrm_feature
+        img_comb_feature = paddle.reshape(combine_feature, shape=[-1, c1])
+
+        out = self.fc1(img_comb_feature)
+        return out
+
+
+class SRNHead(nn.Layer):
+    def __init__(self, in_channels, out_channels, max_text_length, num_heads,
+                 num_encoder_TUs, num_decoder_TUs, hidden_dims, **kwargs):
+        super(SRNHead, self).__init__()
+        self.char_num = out_channels
+        self.max_length = max_text_length
+        self.num_heads = num_heads
+        self.num_encoder_TUs = num_encoder_TUs
+        self.num_decoder_TUs = num_decoder_TUs
+        self.hidden_dims = hidden_dims
+
+        self.pvam = PVAM(
+            in_channels=in_channels,
+            char_num=self.char_num,
+            max_text_length=self.max_length,
+            num_heads=self.num_heads,
+            num_encoder_tus=self.num_encoder_TUs,
+            hidden_dims=self.hidden_dims)
+
+        self.gsrm = GSRM(
+            in_channels=in_channels,
+            char_num=self.char_num,
+            max_text_length=self.max_length,
+            num_heads=self.num_heads,
+            num_encoder_tus=self.num_encoder_TUs,
+            num_decoder_tus=self.num_decoder_TUs,
+            hidden_dims=self.hidden_dims)
+        self.vsfd = VSFD(in_channels=in_channels, char_num=self.char_num)
+
+        self.gsrm.wrap_encoder1.prepare_decoder.emb0 = self.gsrm.wrap_encoder0.prepare_decoder.emb0
+
+    def forward(self, inputs, targets=None):
+        others = targets[-4:]
+        encoder_word_pos = others[0]
+        gsrm_word_pos = others[1]
+        gsrm_slf_attn_bias1 = others[2]
+        gsrm_slf_attn_bias2 = others[3]
+
+        pvam_feature = self.pvam(inputs, encoder_word_pos, gsrm_word_pos)
+
+        gsrm_feature, word_out, gsrm_out = self.gsrm(
+            pvam_feature, gsrm_word_pos, gsrm_slf_attn_bias1,
+            gsrm_slf_attn_bias2)
+
+        final_out = self.vsfd(pvam_feature, gsrm_feature)
+        if not self.training:
+            final_out = F.softmax(final_out, axis=1)
+
+        _, decoded_out = paddle.topk(final_out, k=1)
+
+        predicts = OrderedDict([
+            ('predict', final_out),
+            ('pvam_feature', pvam_feature),
+            ('decoded_out', decoded_out),
+            ('word_out', word_out),
+            ('gsrm_out', gsrm_out),
+        ])
+
+        return predicts

ppocr/modeling/heads/self_attention.py

+# copyright (c) 2020 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import math
+
+import paddle
+from paddle import ParamAttr, nn
+from paddle import nn, ParamAttr
+from paddle.nn import functional as F
+import numpy as np
+gradient_clip = 10
+
+
+class WrapEncoderForFeature(nn.Layer):
+    def __init__(self,
+                 src_vocab_size,
+                 max_length,
+                 n_layer,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd,
+                 postprocess_cmd,
+                 weight_sharing,
+                 bos_idx=0):
+        super(WrapEncoderForFeature, self).__init__()
+
+        self.prepare_encoder = PrepareEncoder(
+            src_vocab_size,
+            d_model,
+            max_length,
+            prepostprocess_dropout,
+            bos_idx=bos_idx,
+            word_emb_param_name="src_word_emb_table")
+        self.encoder = Encoder(n_layer, n_head, d_key, d_value, d_model,
+                               d_inner_hid, prepostprocess_dropout,
+                               attention_dropout, relu_dropout, preprocess_cmd,
+                               postprocess_cmd)
+
+    def forward(self, enc_inputs):
+        conv_features, src_pos, src_slf_attn_bias = enc_inputs
+        enc_input = self.prepare_encoder(conv_features, src_pos)
+        enc_output = self.encoder(enc_input, src_slf_attn_bias)
+        return enc_output
+
+
+class WrapEncoder(nn.Layer):
+    """
+    embedder + encoder
+    """
+
+    def __init__(self,
+                 src_vocab_size,
+                 max_length,
+                 n_layer,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd,
+                 postprocess_cmd,
+                 weight_sharing,
+                 bos_idx=0):
+        super(WrapEncoder, self).__init__()
+
+        self.prepare_decoder = PrepareDecoder(
+            src_vocab_size,
+            d_model,
+            max_length,
+            prepostprocess_dropout,
+            bos_idx=bos_idx)
+        self.encoder = Encoder(n_layer, n_head, d_key, d_value, d_model,
+                               d_inner_hid, prepostprocess_dropout,
+                               attention_dropout, relu_dropout, preprocess_cmd,
+                               postprocess_cmd)
+
+    def forward(self, enc_inputs):
+        src_word, src_pos, src_slf_attn_bias = enc_inputs
+        enc_input = self.prepare_decoder(src_word, src_pos)
+        enc_output = self.encoder(enc_input, src_slf_attn_bias)
+        return enc_output
+
+
+class Encoder(nn.Layer):
+    """
+    encoder
+    """
+
+    def __init__(self,
+                 n_layer,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd="n",
+                 postprocess_cmd="da"):
+
+        super(Encoder, self).__init__()
+
+        self.encoder_layers = list()
+        for i in range(n_layer):
+            self.encoder_layers.append(
+                self.add_sublayer(
+                    "layer_%d" % i,
+                    EncoderLayer(n_head, d_key, d_value, d_model, d_inner_hid,
+                                 prepostprocess_dropout, attention_dropout,
+                                 relu_dropout, preprocess_cmd,
+                                 postprocess_cmd)))
+        self.processer = PrePostProcessLayer(preprocess_cmd, d_model,
+                                             prepostprocess_dropout)
+
+    def forward(self, enc_input, attn_bias):
+        for encoder_layer in self.encoder_layers:
+            enc_output = encoder_layer(enc_input, attn_bias)
+            enc_input = enc_output
+        enc_output = self.processer(enc_output)
+        return enc_output
+
+
+class EncoderLayer(nn.Layer):
+    """
+    EncoderLayer
+    """
+
+    def __init__(self,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd="n",
+                 postprocess_cmd="da"):
+
+        super(EncoderLayer, self).__init__()
+        self.preprocesser1 = PrePostProcessLayer(preprocess_cmd, d_model,
+                                                 prepostprocess_dropout)
+        self.self_attn = MultiHeadAttention(d_key, d_value, d_model, n_head,
+                                            attention_dropout)
+        self.postprocesser1 = PrePostProcessLayer(postprocess_cmd, d_model,
+                                                  prepostprocess_dropout)
+
+        self.preprocesser2 = PrePostProcessLayer(preprocess_cmd, d_model,
+                                                 prepostprocess_dropout)
+        self.ffn = FFN(d_inner_hid, d_model, relu_dropout)
+        self.postprocesser2 = PrePostProcessLayer(postprocess_cmd, d_model,
+                                                  prepostprocess_dropout)
+
+    def forward(self, enc_input, attn_bias):
+        attn_output = self.self_attn(
+            self.preprocesser1(enc_input), None, None, attn_bias)
+        attn_output = self.postprocesser1(attn_output, enc_input)
+        ffn_output = self.ffn(self.preprocesser2(attn_output))
+        ffn_output = self.postprocesser2(ffn_output, attn_output)
+        return ffn_output
+
+
+class MultiHeadAttention(nn.Layer):
+    """
+    Multi-Head Attention
+    """
+
+    def __init__(self, d_key, d_value, d_model, n_head=1, dropout_rate=0.):
+        super(MultiHeadAttention, self).__init__()
+        self.n_head = n_head
+        self.d_key = d_key
+        self.d_value = d_value
+        self.d_model = d_model
+        self.dropout_rate = dropout_rate
+        self.q_fc = paddle.nn.Linear(
+            in_features=d_model, out_features=d_key * n_head, bias_attr=False)
+        self.k_fc = paddle.nn.Linear(
+            in_features=d_model, out_features=d_key * n_head, bias_attr=False)
+        self.v_fc = paddle.nn.Linear(
+            in_features=d_model, out_features=d_value * n_head, bias_attr=False)
+        self.proj_fc = paddle.nn.Linear(
+            in_features=d_value * n_head, out_features=d_model, bias_attr=False)
+
+    def _prepare_qkv(self, queries, keys, values, cache=None):
+        if keys is None:  # self-attention
+            keys, values = queries, queries
+            static_kv = False
+        else:  # cross-attention
+            static_kv = True
+
+        q = self.q_fc(queries)
+        q = paddle.reshape(x=q, shape=[0, 0, self.n_head, self.d_key])
+        q = paddle.transpose(x=q, perm=[0, 2, 1, 3])
+
+        if cache is not None and static_kv and "static_k" in cache:
+            # for encoder-decoder attention in inference and has cached
+            k = cache["static_k"]
+            v = cache["static_v"]
+        else:
+            k = self.k_fc(keys)
+            v = self.v_fc(values)
+            k = paddle.reshape(x=k, shape=[0, 0, self.n_head, self.d_key])
+            k = paddle.transpose(x=k, perm=[0, 2, 1, 3])
+            v = paddle.reshape(x=v, shape=[0, 0, self.n_head, self.d_value])
+            v = paddle.transpose(x=v, perm=[0, 2, 1, 3])
+
+        if cache is not None:
+            if static_kv and not "static_k" in cache:
+                # for encoder-decoder attention in inference and has not cached
+                cache["static_k"], cache["static_v"] = k, v
+            elif not static_kv:
+                # for decoder self-attention in inference
+                cache_k, cache_v = cache["k"], cache["v"]
+                k = paddle.concat([cache_k, k], axis=2)
+                v = paddle.concat([cache_v, v], axis=2)
+                cache["k"], cache["v"] = k, v
+
+        return q, k, v
+
+    def forward(self, queries, keys, values, attn_bias, cache=None):
+        # compute q ,k ,v
+        keys = queries if keys is None else keys
+        values = keys if values is None else values
+        q, k, v = self._prepare_qkv(queries, keys, values, cache)
+
+        # scale dot product attention
+        product = paddle.matmul(x=q, y=k, transpose_y=True)
+        product = product * self.d_model**-0.5
+        if attn_bias is not None:
+            product += attn_bias
+        weights = F.softmax(product)
+        if self.dropout_rate:
+            weights = F.dropout(
+                weights, p=self.dropout_rate, mode="downscale_in_infer")
+        out = paddle.matmul(weights, v)
+
+        # combine heads
+        out = paddle.transpose(out, perm=[0, 2, 1, 3])
+        out = paddle.reshape(x=out, shape=[0, 0, out.shape[2] * out.shape[3]])
+
+        # project to output
+        out = self.proj_fc(out)
+
+        return out
+
+
+class PrePostProcessLayer(nn.Layer):
+    """
+    PrePostProcessLayer
+    """
+
+    def __init__(self, process_cmd, d_model, dropout_rate):
+        super(PrePostProcessLayer, self).__init__()
+        self.process_cmd = process_cmd
+        self.functors = []
+        for cmd in self.process_cmd:
+            if cmd == "a":  # add residual connection
+                self.functors.append(lambda x, y: x + y if y is not None else x)
+            elif cmd == "n":  # add layer normalization
+                self.functors.append(
+                    self.add_sublayer(
+                        "layer_norm_%d" % len(self.sublayers()),
+                        paddle.nn.LayerNorm(
+                            normalized_shape=d_model,
+                            weight_attr=paddle.ParamAttr(
+                                initializer=paddle.nn.initializer.Constant(1.)),
+                            bias_attr=paddle.ParamAttr(
+                                initializer=paddle.nn.initializer.Constant(0.)))))
+            elif cmd == "d":  # add dropout
+                self.functors.append(lambda x: F.dropout(
+                    x, p=dropout_rate, mode="downscale_in_infer")
+                                     if dropout_rate else x)
+
+    def forward(self, x, residual=None):
+        for i, cmd in enumerate(self.process_cmd):
+            if cmd == "a":
+                x = self.functors[i](x, residual)
+            else:
+                x = self.functors[i](x)
+        return x
+
+
+class PrepareEncoder(nn.Layer):
+    def __init__(self,
+                 src_vocab_size,
+                 src_emb_dim,
+                 src_max_len,
+                 dropout_rate=0,
+                 bos_idx=0,
+                 word_emb_param_name=None,
+                 pos_enc_param_name=None):
+        super(PrepareEncoder, self).__init__()
+        self.src_emb_dim = src_emb_dim
+        self.src_max_len = src_max_len
+        self.emb = paddle.nn.Embedding(
+            num_embeddings=self.src_max_len, embedding_dim=self.src_emb_dim)
+        self.dropout_rate = dropout_rate
+
+    def forward(self, src_word, src_pos):
+        src_word_emb = src_word
+        src_word_emb = paddle.cast(src_word_emb, 'float32')
+        src_word_emb = paddle.scale(x=src_word_emb, scale=self.src_emb_dim**0.5)
+        src_pos = paddle.squeeze(src_pos, axis=-1)
+        src_pos_enc = self.emb(src_pos)
+        src_pos_enc.stop_gradient = True
+        enc_input = src_word_emb + src_pos_enc
+        if self.dropout_rate:
+            out = F.dropout(
+                x=enc_input, p=self.dropout_rate, mode="downscale_in_infer")
+        else:
+            out = enc_input
+        return out
+
+
+class PrepareDecoder(nn.Layer):
+    def __init__(self,
+                 src_vocab_size,
+                 src_emb_dim,
+                 src_max_len,
+                 dropout_rate=0,
+                 bos_idx=0,
+                 word_emb_param_name=None,
+                 pos_enc_param_name=None):
+        super(PrepareDecoder, self).__init__()
+        self.src_emb_dim = src_emb_dim
+        """
+        self.emb0 = Embedding(num_embeddings=src_vocab_size,
+                              embedding_dim=src_emb_dim)
+        """
+        self.emb0 = paddle.nn.Embedding(
+            num_embeddings=src_vocab_size,
+            embedding_dim=self.src_emb_dim,
+            padding_idx=bos_idx,
+            weight_attr=paddle.ParamAttr(
+                name=word_emb_param_name,
+                initializer=nn.initializer.Normal(0., src_emb_dim**-0.5)))
+        self.emb1 = paddle.nn.Embedding(
+            num_embeddings=src_max_len,
+            embedding_dim=self.src_emb_dim,
+            weight_attr=paddle.ParamAttr(name=pos_enc_param_name))
+        self.dropout_rate = dropout_rate
+
+    def forward(self, src_word, src_pos):
+        src_word = paddle.cast(src_word, 'int64')
+        src_word = paddle.squeeze(src_word, axis=-1)
+        src_word_emb = self.emb0(src_word)
+        src_word_emb = paddle.scale(x=src_word_emb, scale=self.src_emb_dim**0.5)
+        src_pos = paddle.squeeze(src_pos, axis=-1)
+        src_pos_enc = self.emb1(src_pos)
+        src_pos_enc.stop_gradient = True
+        enc_input = src_word_emb + src_pos_enc
+        if self.dropout_rate:
+            out = F.dropout(
+                x=enc_input, p=self.dropout_rate, mode="downscale_in_infer")
+        else:
+            out = enc_input
+        return out
+
+
+class FFN(nn.Layer):
+    """
+    Feed-Forward Network
+    """
+
+    def __init__(self, d_inner_hid, d_model, dropout_rate):
+        super(FFN, self).__init__()
+        self.dropout_rate = dropout_rate
+        self.fc1 = paddle.nn.Linear(
+            in_features=d_model, out_features=d_inner_hid)
+        self.fc2 = paddle.nn.Linear(
+            in_features=d_inner_hid, out_features=d_model)
+
+    def forward(self, x):
+        hidden = self.fc1(x)
+        hidden = F.relu(hidden)
+        if self.dropout_rate:
+            hidden = F.dropout(
+                hidden, p=self.dropout_rate, mode="downscale_in_infer")
+        out = self.fc2(hidden)
+        return out

ppocr/modeling/heads/table_att_head.py

+# copyright (c) 2021 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import paddle
+import paddle.nn as nn
+import paddle.nn.functional as F
+import numpy as np
+
+
+class TableAttentionHead(nn.Layer):
+    def __init__(self,
+                 in_channels,
+                 hidden_size,
+                 loc_type,
+                 in_max_len=488,
+                 max_text_length=100,
+                 max_elem_length=800,
+                 max_cell_num=500,
+                 **kwargs):
+        super(TableAttentionHead, self).__init__()
+        self.input_size = in_channels[-1]
+        self.hidden_size = hidden_size
+        self.elem_num = 30
+        self.max_text_length = max_text_length
+        self.max_elem_length = max_elem_length
+        self.max_cell_num = max_cell_num
+
+        self.structure_attention_cell = AttentionGRUCell(
+            self.input_size, hidden_size, self.elem_num, use_gru=False)
+        self.structure_generator = nn.Linear(hidden_size, self.elem_num)
+        self.loc_type = loc_type
+        self.in_max_len = in_max_len
+
+        if self.loc_type == 1:
+            self.loc_generator = nn.Linear(hidden_size, 4)
+        else:
+            if self.in_max_len == 640:
+                self.loc_fea_trans = nn.Linear(400, self.max_elem_length + 1)
+            elif self.in_max_len == 800:
+                self.loc_fea_trans = nn.Linear(625, self.max_elem_length + 1)
+            else:
+                self.loc_fea_trans = nn.Linear(256, self.max_elem_length + 1)
+            self.loc_generator = nn.Linear(self.input_size + hidden_size, 4)
+
+    def _char_to_onehot(self, input_char, onehot_dim):
+        input_ont_hot = F.one_hot(input_char, onehot_dim)
+        return input_ont_hot
+
+    def forward(self, inputs, targets=None):
+        # if and else branch are both needed when you want to assign a variable
+        # if you modify the var in just one branch, then the modification will not work.
+        fea = inputs[-1]
+        if len(fea.shape) == 3:
+            pass
+        else:
+            last_shape = int(np.prod(fea.shape[2:]))  # gry added
+            fea = paddle.reshape(fea, [fea.shape[0], fea.shape[1], last_shape])
+            fea = fea.transpose([0, 2, 1])  # (NTC)(batch, width, channels)
+        batch_size = fea.shape[0]
+
+        hidden = paddle.zeros((batch_size, self.hidden_size))
+        output_hiddens = []
+        if self.training and targets is not None:
+            structure = targets[0]
+            for i in range(self.max_elem_length + 1):
+                elem_onehots = self._char_to_onehot(
+                    structure[:, i], onehot_dim=self.elem_num)
+                (outputs, hidden), alpha = self.structure_attention_cell(
+                    hidden, fea, elem_onehots)
+                output_hiddens.append(paddle.unsqueeze(outputs, axis=1))
+            output = paddle.concat(output_hiddens, axis=1)
+            structure_probs = self.structure_generator(output)
+            if self.loc_type == 1:
+                loc_preds = self.loc_generator(output)
+                loc_preds = F.sigmoid(loc_preds)
+            else:
+                loc_fea = fea.transpose([0, 2, 1])
+                loc_fea = self.loc_fea_trans(loc_fea)
+                loc_fea = loc_fea.transpose([0, 2, 1])
+                loc_concat = paddle.concat([output, loc_fea], axis=2)
+                loc_preds = self.loc_generator(loc_concat)
+                loc_preds = F.sigmoid(loc_preds)
+        else:
+            temp_elem = paddle.zeros(shape=[batch_size], dtype="int32")
+            structure_probs = None
+            loc_preds = None
+            elem_onehots = None
+            outputs = None
+            alpha = None
+            max_elem_length = paddle.to_tensor(self.max_elem_length)
+            i = 0
+            while i < max_elem_length + 1:
+                elem_onehots = self._char_to_onehot(
+                    temp_elem, onehot_dim=self.elem_num)
+                (outputs, hidden), alpha = self.structure_attention_cell(
+                    hidden, fea, elem_onehots)
+                output_hiddens.append(paddle.unsqueeze(outputs, axis=1))
+                structure_probs_step = self.structure_generator(outputs)
+                temp_elem = structure_probs_step.argmax(axis=1, dtype="int32")
+                i += 1
+
+            output = paddle.concat(output_hiddens, axis=1)
+            structure_probs = self.structure_generator(output)
+            structure_probs = F.softmax(structure_probs)
+            if self.loc_type == 1:
+                loc_preds = self.loc_generator(output)
+                loc_preds = F.sigmoid(loc_preds)
+            else:
+                loc_fea = fea.transpose([0, 2, 1])
+                loc_fea = self.loc_fea_trans(loc_fea)
+                loc_fea = loc_fea.transpose([0, 2, 1])
+                loc_concat = paddle.concat([output, loc_fea], axis=2)
+                loc_preds = self.loc_generator(loc_concat)
+                loc_preds = F.sigmoid(loc_preds)
+        return {'structure_probs': structure_probs, 'loc_preds': loc_preds}
+
+
+class AttentionGRUCell(nn.Layer):
+    def __init__(self, input_size, hidden_size, num_embeddings, use_gru=False):
+        super(AttentionGRUCell, self).__init__()
+        self.i2h = nn.Linear(input_size, hidden_size, bias_attr=False)
+        self.h2h = nn.Linear(hidden_size, hidden_size)
+        self.score = nn.Linear(hidden_size, 1, bias_attr=False)
+        self.rnn = nn.GRUCell(
+            input_size=input_size + num_embeddings, hidden_size=hidden_size)
+        self.hidden_size = hidden_size
+
+    def forward(self, prev_hidden, batch_H, char_onehots):
+        batch_H_proj = self.i2h(batch_H)
+        prev_hidden_proj = paddle.unsqueeze(self.h2h(prev_hidden), axis=1)
+        res = paddle.add(batch_H_proj, prev_hidden_proj)
+        res = paddle.tanh(res)
+        e = self.score(res)
+        alpha = F.softmax(e, axis=1)
+        alpha = paddle.transpose(alpha, [0, 2, 1])
+        context = paddle.squeeze(paddle.mm(alpha, batch_H), axis=1)
+        concat_context = paddle.concat([context, char_onehots], 1)
+        cur_hidden = self.rnn(concat_context, prev_hidden)
+        return cur_hidden, alpha
+
+
+class AttentionLSTM(nn.Layer):
+    def __init__(self, in_channels, out_channels, hidden_size, **kwargs):
+        super(AttentionLSTM, self).__init__()
+        self.input_size = in_channels
+        self.hidden_size = hidden_size
+        self.num_classes = out_channels
+
+        self.attention_cell = AttentionLSTMCell(
+            in_channels, hidden_size, out_channels, use_gru=False)
+        self.generator = nn.Linear(hidden_size, out_channels)
+
+    def _char_to_onehot(self, input_char, onehot_dim):
+        input_ont_hot = F.one_hot(input_char, onehot_dim)
+        return input_ont_hot
+
+    def forward(self, inputs, targets=None, batch_max_length=25):
+        batch_size = inputs.shape[0]
+        num_steps = batch_max_length
+
+        hidden = (paddle.zeros((batch_size, self.hidden_size)), paddle.zeros(
+            (batch_size, self.hidden_size)))
+        output_hiddens = []
+
+        if targets is not None:
+            for i in range(num_steps):
+                # one-hot vectors for a i-th char
+                char_onehots = self._char_to_onehot(
+                    targets[:, i], onehot_dim=self.num_classes)
+                hidden, alpha = self.attention_cell(hidden, inputs,
+                                                    char_onehots)
+
+                hidden = (hidden[1][0], hidden[1][1])
+                output_hiddens.append(paddle.unsqueeze(hidden[0], axis=1))
+            output = paddle.concat(output_hiddens, axis=1)
+            probs = self.generator(output)
+
+        else:
+            targets = paddle.zeros(shape=[batch_size], dtype="int32")
+            probs = None
+
+            for i in range(num_steps):
+                char_onehots = self._char_to_onehot(
+                    targets, onehot_dim=self.num_classes)
+                hidden, alpha = self.attention_cell(hidden, inputs,
+                                                    char_onehots)
+                probs_step = self.generator(hidden[0])
+                hidden = (hidden[1][0], hidden[1][1])
+                if probs is None:
+                    probs = paddle.unsqueeze(probs_step, axis=1)
+                else:
+                    probs = paddle.concat(
+                        [probs, paddle.unsqueeze(
+                            probs_step, axis=1)], axis=1)
+
+                next_input = probs_step.argmax(axis=1)
+
+                targets = next_input
+
+        return probs
+
+
+class AttentionLSTMCell(nn.Layer):
+    def __init__(self, input_size, hidden_size, num_embeddings, use_gru=False):
+        super(AttentionLSTMCell, self).__init__()
+        self.i2h = nn.Linear(input_size, hidden_size, bias_attr=False)
+        self.h2h = nn.Linear(hidden_size, hidden_size)
+        self.score = nn.Linear(hidden_size, 1, bias_attr=False)
+        if not use_gru:
+            self.rnn = nn.LSTMCell(
+                input_size=input_size + num_embeddings, hidden_size=hidden_size)
+        else:
+            self.rnn = nn.GRUCell(
+                input_size=input_size + num_embeddings, hidden_size=hidden_size)
+
+        self.hidden_size = hidden_size
+
+    def forward(self, prev_hidden, batch_H, char_onehots):
+        batch_H_proj = self.i2h(batch_H)
+        prev_hidden_proj = paddle.unsqueeze(self.h2h(prev_hidden[0]), axis=1)
+        res = paddle.add(batch_H_proj, prev_hidden_proj)
+        res = paddle.tanh(res)
+        e = self.score(res)
+
+        alpha = F.softmax(e, axis=1)
+        alpha = paddle.transpose(alpha, [0, 2, 1])
+        context = paddle.squeeze(paddle.mm(alpha, batch_H), axis=1)
+        concat_context = paddle.concat([context, char_onehots], 1)
+        cur_hidden = self.rnn(concat_context, prev_hidden)
+
+        return cur_hidden, alpha

ppocr/modeling/necks/__init__.py

+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+__all__ = ['build_neck']
+
+
+def build_neck(config):
+    from .db_fpn import DBFPN, RSEFPN, LKPAN
+    from .east_fpn import EASTFPN
+    from .sast_fpn import SASTFPN
+    from .rnn import SequenceEncoder
+    from .pg_fpn import PGFPN
+    from .table_fpn import TableFPN
+    from .fpn import FPN
+    from .fce_fpn import FCEFPN
+    from .pren_fpn import PRENFPN
+    support_dict = [
+        'FPN', 'FCEFPN', 'LKPAN', 'DBFPN', 'RSEFPN', 'EASTFPN', 'SASTFPN',
+        'SequenceEncoder', 'PGFPN', 'TableFPN', 'PRENFPN'
+    ]
+
+    module_name = config.pop('name')
+    assert module_name in support_dict, Exception('neck only support {}'.format(
+        support_dict))
+    module_class = eval(module_name)(**config)
+    return module_class