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Commit edf8c8f5 authored by Chen Chen's avatar Chen Chen Committed by A. Unique TensorFlower
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Add a colab to introduce nlp/modeling library with examples showing how to... 

Add a colab to introduce nlp/modeling library with examples showing how to build pretrain/span labeling/classification models.

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{
"cells": [
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "80xnUmoI7fBX"
},
"source": [
"##### Copyright 2020 The TensorFlow Authors."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"cellView": "form",
"colab": {},
"colab_type": "code",
"id": "8nvTnfs6Q692"
},
"outputs": [],
"source": [
"#@title Licensed under the Apache License, Version 2.0 (the \"License\");\n",
"# you may not use this file except in compliance with the License.\n",
"# You may obtain a copy of the License at\n",
"#\n",
"# https://www.apache.org/licenses/LICENSE-2.0\n",
"#\n",
"# Unless required by applicable law or agreed to in writing, software\n",
"# distributed under the License is distributed on an \"AS IS\" BASIS,\n",
"# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n",
"# See the License for the specific language governing permissions and\n",
"# limitations under the License."
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "WmfcMK5P5C1G"
},
"source": [
"# Introduction to the TensorFlow Models NLP library"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "cH-oJ8R6AHMK"
},
"source": [
"\u003ctable class=\"tfo-notebook-buttons\" align=\"left\"\u003e\n",
" \u003ctd\u003e\n",
" \u003ca target=\"_blank\" href=\"https://www.tensorflow.org/official_models/nlp/nlp_modeling_library_intro\"\u003e\u003cimg src=\"https://www.tensorflow.org/images/tf_logo_32px.png\" /\u003eView on TensorFlow.org\u003c/a\u003e\n",
" \u003c/td\u003e\n",
" \u003ctd\u003e\n",
" \u003ca target=\"_blank\" href=\"https://colab.research.google.com/github/tensorflow/models/blob/master/official/colab/nlp/nlp_modeling_library_intro.ipynb\"\u003e\u003cimg src=\"https://www.tensorflow.org/images/colab_logo_32px.png\" /\u003eRun in Google Colab\u003c/a\u003e\n",
" \u003c/td\u003e\n",
" \u003ctd\u003e\n",
" \u003ca target=\"_blank\" href=\"https://github.com/tensorflow/models/blob/master/official/colab/nlp/nlp_modeling_library_intro.ipynb\"\u003e\u003cimg src=\"https://www.tensorflow.org/images/GitHub-Mark-32px.png\" /\u003eView source on GitHub\u003c/a\u003e\n",
" \u003c/td\u003e\n",
" \u003ctd\u003e\n",
" \u003ca href=\"https://storage.googleapis.com/tensorflow_docs/models/official/colab/nlp/nlp_modeling_library_intro.ipynb\"\u003e\u003cimg src=\"https://www.tensorflow.org/images/download_logo_32px.png\" /\u003eDownload notebook\u003c/a\u003e\n",
" \u003c/td\u003e\n",
"\u003c/table\u003e"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "0H_EFIhq4-MJ"
},
"source": [
"## Learning objectives\n",
"\n",
"In this Colab notebook, you will learn how to build transformer-based models for common NLP tasks including pretraining, span labelling and classification using the building blocks from [NLP modeling library](https://github.com/tensorflow/models/tree/master/official/nlp/modeling)."
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "2N97-dps_nUk"
},
"source": [
"## Install and import"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "459ygAVl_rg0"
},
"source": [
"### Install the TensorFlow Model Garden pip package\n",
"\n",
"* `tf-models-nightly` is the nightly Model Garden package created daily automatically.\n",
"* `pip` will install all models and dependencies automatically."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "Y-qGkdh6_sZc"
},
"outputs": [],
"source": [
"!pip install -q tf-nightly\n",
"!pip install -q tf-models-nightly"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "e4huSSwyAG_5"
},
"source": [
"### Import Tensorflow and other libraries"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "jqYXqtjBAJd9"
},
"outputs": [],
"source": [
"import numpy as np\n",
"import tensorflow as tf\n",
"\n",
"from official.nlp import modeling\n",
"from official.nlp.modeling import layers, losses, models, networks"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "djBQWjvy-60Y"
},
"source": [
"## BERT pretraining model\n",
"\n",
"BERT ([Pre-training of Deep Bidirectional Transformers for Language Understanding](https://arxiv.org/abs/1810.04805)) introduced the method of pre-training language representations on a large text corpus and then using that model for downstream NLP tasks.\n",
"\n",
"In this section, we will learn how to build a model to pretrain BERT on the masked language modeling task and next sentence prediction task. For simplicity, we only show the minimum example and use dummy data."
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "MKuHVlsCHmiq"
},
"source": [
"### Build a `BertPretrainer` model wrapping `TransformerEncoder`\n",
"\n",
"The [TransformerEncoder](https://github.com/tensorflow/models/blob/master/official/nlp/modeling/networks/transformer_encoder.py) implements the Transformer-based encoder as described in [BERT paper](https://arxiv.org/abs/1810.04805). It includes the embedding lookups and transformer layers, but not the masked language model or classification task networks.\n",
"\n",
"The [BertPretrainer](https://github.com/tensorflow/models/blob/master/official/nlp/modeling/models/bert_pretrainer.py) allows a user to pass in a transformer stack, and instantiates the masked language model and classification networks that are used to create the training objectives."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "EXkcXz-9BwB3"
},
"outputs": [],
"source": [
"# Build a small transformer network.\n",
"vocab_size = 100\n",
"sequence_length = 16\n",
"network = modeling.networks.TransformerEncoder(\n",
" vocab_size=vocab_size, num_layers=2, sequence_length=16)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "0NH5irV5KTMS"
},
"source": [
"Inspecting the encoder, we see it contains few embedding layers, stacked `Transformer` layers and are connected to three input layers:\n",
"\n",
"`input_word_ids`, `input_type_ids` and `input_mask`.\n"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "lZNoZkBrIoff"
},
"outputs": [],
"source": [
"tf.keras.utils.plot_model(network, show_shapes=True, dpi=48)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "o7eFOZXiIl-b"
},
"outputs": [],
"source": [
"# Create a BERT pretrainer with the created network.\n",
"num_token_predictions = 8\n",
"bert_pretrainer = modeling.models.BertPretrainer(\n",
" network, num_classes=2, num_token_predictions=num_token_predictions, output='predictions')"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "d5h5HT7gNHx_"
},
"source": [
"Inspecting the `bert_pretrainer`, we see it wraps the `encoder` with additional `MaskedLM` and `Classification` heads."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "2tcNfm03IBF7"
},
"outputs": [],
"source": [
"tf.keras.utils.plot_model(bert_pretrainer, show_shapes=True, dpi=48)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "F2oHrXGUIS0M"
},
"outputs": [],
"source": [
"# We can feed some dummy data to get masked language model and sentence output.\n",
"batch_size = 2\n",
"word_id_data = np.random.randint(vocab_size, size=(batch_size, sequence_length))\n",
"mask_data = np.random.randint(2, size=(batch_size, sequence_length))\n",
"type_id_data = np.random.randint(2, size=(batch_size, sequence_length))\n",
"masked_lm_positions_data = np.random.randint(2, size=(batch_size, num_token_predictions))\n",
"\n",
"outputs = bert_pretrainer(\n",
" [word_id_data, mask_data, type_id_data, masked_lm_positions_data])\n",
"lm_output = outputs[\"masked_lm\"]\n",
"sentence_output = outputs[\"classification\"]\n",
"print(lm_output)\n",
"print(sentence_output)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "bnx3UCHniCS5"
},
"source": [
"### Compute loss\n",
"Next, we can use `lm_output` and `sentence_output` to compute `loss`."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "k30H4Q86f52x"
},
"outputs": [],
"source": [
"masked_lm_ids_data = np.random.randint(vocab_size, size=(batch_size, num_token_predictions))\n",
"masked_lm_weights_data = np.random.randint(2, size=(batch_size, num_token_predictions))\n",
"next_sentence_labels_data = np.random.randint(2, size=(batch_size))\n",
"\n",
"mlm_loss = modeling.losses.weighted_sparse_categorical_crossentropy_loss(\n",
" labels=masked_lm_ids_data,\n",
" predictions=lm_output,\n",
" weights=masked_lm_weights_data)\n",
"sentence_loss = modeling.losses.weighted_sparse_categorical_crossentropy_loss(\n",
" labels=next_sentence_labels_data,\n",
" predictions=sentence_output)\n",
"loss = mlm_loss + sentence_loss\n",
"print(loss)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "wrmSs8GjHxVw"
},
"source": [
"With the loss, you can optimize the model.\n",
"After training, we can save the weights of TransformerEncoder for the downstream fine-tuning tasks. Please see [run_pretraining.py](https://github.com/tensorflow/models/blob/master/official/nlp/bert/run_pretraining.py) for the full example.\n",
"\n"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "k8cQVFvBCV4s"
},
"source": [
"## Span labeling model\n",
"\n",
"Span labeling is the task to assign labels to a span of the text, for example, label a span of text as the answer of a given question.\n",
"\n",
"In this section, we will learn how to build a span labeling model. Again, we use dummy data for simplicity."
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "xrLLEWpfknUW"
},
"source": [
"### Build a BertSpanLabeler wrapping TransformerEncoder\n",
"\n",
"[BertSpanLabeler](https://github.com/tensorflow/models/blob/master/official/nlp/modeling/models/bert_span_labeler.py) implements a simple single-span start-end predictor (that is, a model that predicts two values: a start token index and an end token index), suitable for SQuAD-style tasks.\n",
"\n",
"Note that `BertSpanLabeler` wraps a `TransformerEncoder`, the weights of which can be restored from the above pretraining model.\n"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "B941M4iUCejO"
},
"outputs": [],
"source": [
"network = modeling.networks.TransformerEncoder(\n",
" vocab_size=vocab_size, num_layers=2, sequence_length=sequence_length)\n",
"\n",
"# Create a BERT trainer with the created network.\n",
"bert_span_labeler = modeling.models.BertSpanLabeler(network)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "QpB9pgj4PpMg"
},
"source": [
"Inspecting the `bert_span_labeler`, we see it wraps the encoder with additional `SpanLabeling` that outputs `start_position` and `end_postion`."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "RbqRNJCLJu4H"
},
"outputs": [],
"source": [
"tf.keras.utils.plot_model(bert_span_labeler, show_shapes=True, dpi=48)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "fUf1vRxZJwio"
},
"outputs": [],
"source": [
"# Create a set of 2-dimensional data tensors to feed into the model.\n",
"word_id_data = np.random.randint(vocab_size, size=(batch_size, sequence_length))\n",
"mask_data = np.random.randint(2, size=(batch_size, sequence_length))\n",
"type_id_data = np.random.randint(2, size=(batch_size, sequence_length))\n",
"\n",
"# Feed the data to the model.\n",
"start_logits, end_logits = bert_span_labeler([word_id_data, mask_data, type_id_data])\n",
"print(start_logits)\n",
"print(end_logits)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "WqhgQaN1lt-G"
},
"source": [
"### Compute loss\n",
"With `start_logits` and `end_logits`, we can compute loss:"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "waqs6azNl3Nn"
},
"outputs": [],
"source": [
"start_positions = np.random.randint(sequence_length, size=(batch_size))\n",
"end_positions = np.random.randint(sequence_length, size=(batch_size))\n",
"\n",
"start_loss = tf.keras.losses.sparse_categorical_crossentropy(\n",
" start_positions, start_logits, from_logits=True)\n",
"end_loss = tf.keras.losses.sparse_categorical_crossentropy(\n",
" end_positions, end_logits, from_logits=True)\n",
"\n",
"total_loss = (tf.reduce_mean(start_loss) + tf.reduce_mean(end_loss)) / 2\n",
"print(total_loss)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "Zdf03YtZmd_d"
},
"source": [
"With the `loss`, you can optimize the model. Please see [run_squad.py](https://github.com/tensorflow/models/blob/master/official/nlp/bert/run_squad.py) for the full example."
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "0A1XnGSTChg9"
},
"source": [
"## Classification model\n",
"\n",
"In the last section, we show how to build a text classification model.\n"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "MSK8OpZgnQa9"
},
"source": [
"### Build a BertClassifier model wrapping TransformerEncoder\n",
"\n",
"[BertClassifier](https://github.com/tensorflow/models/blob/master/official/nlp/modeling/models/bert_classifier.py) implements a simple token classification model containing a single classification head using the `TokenClassification` network."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "cXXCsffkCphk"
},
"outputs": [],
"source": [
"network = modeling.networks.TransformerEncoder(\n",
" vocab_size=vocab_size, num_layers=2, sequence_length=sequence_length)\n",
"\n",
"# Create a BERT trainer with the created network.\n",
"num_classes = 2\n",
"bert_classifier = modeling.models.BertClassifier(\n",
" network, num_classes=num_classes)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "8tZKueKYP4bB"
},
"source": [
"Inspecting the `bert_classifier`, we see it wraps the `encoder` with additional `Classification` head."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "snlutm9ZJgEZ"
},
"outputs": [],
"source": [
"tf.keras.utils.plot_model(bert_classifier, show_shapes=True, dpi=48)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "yyHPHsqBJkCz"
},
"outputs": [],
"source": [
"# Create a set of 2-dimensional data tensors to feed into the model.\n",
"word_id_data = np.random.randint(vocab_size, size=(batch_size, sequence_length))\n",
"mask_data = np.random.randint(2, size=(batch_size, sequence_length))\n",
"type_id_data = np.random.randint(2, size=(batch_size, sequence_length))\n",
"\n",
"# Feed the data to the model.\n",
"logits = bert_classifier([word_id_data, mask_data, type_id_data])\n",
"print(logits)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "w--a2mg4nzKm"
},
"source": [
"### Compute loss\n",
"\n",
"With `logits`, we can compute `loss`:"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"colab": {},
"colab_type": "code",
"id": "9X0S1DoFn_5Q"
},
"outputs": [],
"source": [
"labels = np.random.randint(num_classes, size=(batch_size))\n",
"\n",
"loss = modeling.losses.weighted_sparse_categorical_crossentropy_loss(\n",
" labels=labels, predictions=tf.nn.log_softmax(logits, axis=-1))\n",
"print(loss)"
]
},
{
"cell_type": "markdown",
"metadata": {
"colab_type": "text",
"id": "mzBqOylZo3og"
},
"source": [
"With the `loss`, you can optimize the model. Please see [run_classifier.py](https://github.com/tensorflow/models/blob/master/official/nlp/bert/run_classifier.py) or the colab [fine_tuning_bert.ipynb](https://github.com/tensorflow/models/blob/master/official/colab/fine_tuning_bert.ipynb) for the full example."
]
}
],
"metadata": {
"colab": {
"collapsed_sections": [],
"name": "Introduction to the TensorFlow Models NLP library",
"private_outputs": true,
"provenance": [],
"toc_visible": true
},
"kernelspec": {
"display_name": "Python 3",
"name": "python3"
}
},
"nbformat": 4,
"nbformat_minor": 0
}
official/nlp/modeling/README.md
View file @ edf8c8f5
# NLP Modeling Library
This libary provides a set of Keras primitives (Layers, Networks, and Models)
This library provides a set of Keras primitives (Layers, Networks, and Models)
that can be assembled into transformer-based models. They are
flexible, validated, interoperable, and both TF1 and TF2 compatible.
......@@ -16,6 +16,10 @@ standardized configuration.
* [`losses`](losses) contains common loss computation used in NLP tasks.
Please see the colab
[Introduction_to_NLP_Modeling_Library.ipynb](https://colab.sandbox.google.com/github/tensorflow/models/blob/master/official/colab/nlp/nlp_modeling_library_intro.ipynb)
for how to build transformer-based NLP models using above primitives.
Besides the pre-defined primitives, it also provides scaffold classes to allow
easy experimentation with noval achitectures, e.g., you don’t need to fork a whole Transformer object to try a different kind of attention primitive, for instance.
......
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