Adds an op to handle pre-computed word embeddings.

This change adds an op that will take a text vocabulary file, read
it, and use it to create a pre-computed word embedding vector.

syntaxnet/dragnn/python/BUILD

@@ -89,6 +89,7 @@ py_library(
     srcs = ["network_units.py"],
     deps = [
         ":dragnn_ops",
+        "//syntaxnet:syntaxnet_ops",
         "//syntaxnet/util:check",
         "//syntaxnet/util:pyregistry",
         "@org_tensorflow//tensorflow:tensorflow_py",

syntaxnet/dragnn/python/network_units.py

@@ -15,9 +15,11 @@
 
 """Basic network units used in assembling DRAGNN graphs."""
 
-from abc import ABCMeta
-from abc import abstractmethod
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
 
+import abc
 
 import tensorflow as tf
 from tensorflow.python.ops import nn
@@ -25,6 +27,7 @@ from tensorflow.python.ops import tensor_array_ops as ta
 from tensorflow.python.platform import tf_logging as logging
 
 from dragnn.python import dragnn_ops
+from syntaxnet import syntaxnet_ops
 from syntaxnet.util import check
 from syntaxnet.util import registry
 
@@ -135,11 +138,11 @@ def add_embeddings(channel_id, feature_spec, seed=None):
       raise RuntimeError('vocab resource contains more than one part:\n%s',
                          str(feature_spec.vocab))
     seed1, seed2 = tf.get_seed(seed)
-    embeddings = dragnn_ops.dragnn_embedding_initializer(
-        embedding_input=feature_spec.pretrained_embedding_matrix.part[0]
-        .file_pattern,
-        vocab=feature_spec.vocab.part[0].file_pattern,
-        scaling_coefficient=1.0,
+    embeddings = syntaxnet_ops.word_embedding_initializer(
+        vectors=feature_spec.pretrained_embedding_matrix.part[0].file_pattern,
+        vocabulary=feature_spec.vocab.part[0].file_pattern,
+        num_special_embeddings=1,
+        embedding_init=1.0,
         seed=seed1,
         seed2=seed2)
     return tf.get_variable(name, initializer=tf.reshape(embeddings, shape))
@@ -626,7 +629,7 @@ class NetworkUnitInterface(object):
     layers (list): List of Layer objects to track network layers that should
       be written to Tensors during training and inference.
   """
-  __metaclass__ = ABCMeta  # required for @abstractmethod
+  __metaclass__ = abc.ABCMeta  # required for @abstractmethod
 
   def __init__(self, component, init_layers=None, init_context_layers=None):
     """Initializes parameters for embedding matrices.
@@ -738,7 +741,7 @@ class NetworkUnitInterface(object):
               [attention_hidden_layer_size, component.num_actions],
               initializer=tf.random_normal_initializer(stddev=1e-4)))
 
-  @abstractmethod
+  @abc.abstractmethod
   def create(self,
              fixed_embeddings,
              linked_embeddings,

syntaxnet/syntaxnet/BUILD

@@ -747,6 +747,15 @@ py_library(
     data = [":parser_ops.so"],
 )
 
+py_library(
+    name = "syntaxnet_ops",
+    srcs = ["syntaxnet_ops.py"],
+    deps = [
+        ":parser_ops",
+        ":load_parser_ops_py",
+    ],
+)
+
 py_library(
     name = "graph_builder",
     srcs = ["graph_builder.py"],

syntaxnet/syntaxnet/ops/parser_ops.cc

@@ -247,7 +247,10 @@ weights: vector of weight extracted from the SparseFeatures proto.
 REGISTER_OP("WordEmbeddingInitializer")
     .Output("word_embeddings: float")
     .Attr("vectors: string")
-    .Attr("task_context: string")
+    .Attr("task_context: string = ''")
+    .Attr("vocabulary: string = ''")
+    .Attr("cache_vectors_locally: bool = true")
+    .Attr("num_special_embeddings: int = 3")
     .Attr("embedding_init: float = 1.0")
     .Attr("seed: int = 0")
     .Attr("seed2: int = 0")
@@ -255,9 +258,17 @@ REGISTER_OP("WordEmbeddingInitializer")
 Reads word embeddings from an sstable of dist_belief.TokenEmbedding protos for
 every word specified in a text vocabulary file.
 
-word_embeddings: a tensor containing word embeddings from the specified sstable.
-vectors: path to recordio of word embedding vectors.
-task_context: file path at which to read the task context.
+word_embeddings: a tensor containing word embeddings from the specified table.
+vectors: path to TF record file of word embedding vectors.
+task_context: file path at which to read the task context, for its "word-map"
+  input.  Exactly one of `task_context` or `vocabulary` must be specified.
+vocabulary: path to vocabulary file, which contains one unique word per line, in
+  order.  Exactly one of `task_context` or `vocabulary` must be specified.
+cache_vectors_locally: Whether to cache the vectors file to a local temp file
+  before parsing it.  This greatly reduces initialization time when the vectors
+  are stored remotely, but requires that "/tmp" has sufficient space.
+num_special_embeddings: Number of special embeddings to allocate, in addition to
+  those allocated for real words.
 embedding_init: embedding vectors that are not found in the input sstable are
   initialized randomly from a normal distribution with zero mean and
   std dev = embedding_init / sqrt(embedding_size).

syntaxnet/syntaxnet/reader_ops.cc

@@ -34,9 +34,11 @@ limitations under the License.
 #include "tensorflow/core/framework/op_kernel.h"
 #include "tensorflow/core/framework/tensor.h"
 #include "tensorflow/core/framework/tensor_shape.h"
+#include "tensorflow/core/lib/core/errors.h"
 #include "tensorflow/core/lib/core/status.h"
 #include "tensorflow/core/lib/io/table.h"
 #include "tensorflow/core/lib/io/table_options.h"
+#include "tensorflow/core/lib/strings/str_util.h"
 #include "tensorflow/core/lib/strings/stringprintf.h"
 #include "tensorflow/core/platform/env.h"
 
@@ -439,14 +441,18 @@ class WordEmbeddingInitializer : public OpKernel {
  public:
   explicit WordEmbeddingInitializer(OpKernelConstruction *context)
       : OpKernel(context) {
-    string file_path, data;
-    OP_REQUIRES_OK(context, context->GetAttr("task_context", &file_path));
-    OP_REQUIRES_OK(context, ReadFileToString(tensorflow::Env::Default(),
-                                             file_path, &data));
-    OP_REQUIRES(context,
-                TextFormat::ParseFromString(data, task_context_.mutable_spec()),
-                InvalidArgument("Could not parse task context at ", file_path));
+    OP_REQUIRES_OK(context,
+                   context->GetAttr("task_context", &task_context_path_));
+    OP_REQUIRES_OK(context, context->GetAttr("vocabulary", &vocabulary_path_));
+    OP_REQUIRES(
+        context, task_context_path_.empty() != vocabulary_path_.empty(),
+        InvalidArgument(
+            "Exactly one of task_context or vocabulary must be specified"));
     OP_REQUIRES_OK(context, context->GetAttr("vectors", &vectors_path_));
+    OP_REQUIRES_OK(context, context->GetAttr("cache_vectors_locally",
+                                             &cache_vectors_locally_));
+    OP_REQUIRES_OK(context, context->GetAttr("num_special_embeddings",
+                                             &num_special_embeddings_));
     OP_REQUIRES_OK(context,
                    context->GetAttr("embedding_init", &embedding_init_));
 
@@ -462,43 +468,117 @@ class WordEmbeddingInitializer : public OpKernel {
   }
 
   void Compute(OpKernelContext *context) override {
-    // Loads words from vocabulary with mapping to ids.
-    string path = TaskContext::InputFile(*task_context_.GetInput("word-map"));
-    const TermFrequencyMap *word_map =
-        SharedStoreUtils::GetWithDefaultName<TermFrequencyMap>(path, 0, 0);
-    unordered_map<string, int64> vocab;
-    for (int i = 0; i < word_map->Size(); ++i) {
-      vocab[word_map->GetTerm(i)] = i;
-    }
+    std::unordered_map<string, int64> vocab;
+    OP_REQUIRES_OK(context, LoadVocabulary(&vocab));
 
-    // Creates a reader pointing to a local copy of the vectors recordio.
-    string tmp_vectors_path;
-    OP_REQUIRES_OK(context, CopyToTmpPath(vectors_path_, &tmp_vectors_path));
-    ProtoRecordReader reader(tmp_vectors_path);
+    string vectors_path = vectors_path_;
+    if (cache_vectors_locally_) {
+      OP_REQUIRES_OK(context, CopyToTmpPath(vectors_path_, &vectors_path));
+    }
+    ProtoRecordReader reader(vectors_path);
 
-    // Loads the embedding vectors into a matrix.
+    // Load the embedding vectors into a matrix.  Since the |embedding_matrix|
+    // output cannot be allocated until the embedding dimension is known, delay
+    // allocation until the first iteration of the loop.
     Tensor *embedding_matrix = nullptr;
     TokenEmbedding embedding;
     while (reader.Read(&embedding) == tensorflow::Status::OK()) {
       if (embedding_matrix == nullptr) {
-        const int embedding_size = embedding.vector().values_size();
-        OP_REQUIRES_OK(
-            context, context->allocate_output(
-                         0, TensorShape({word_map->Size() + 3, embedding_size}),
+        OP_REQUIRES_OK(context,
+                       InitRandomEmbeddingMatrix(vocab, embedding, context,
                                                  &embedding_matrix));
-        auto matrix = embedding_matrix->matrix<float>();
-        Eigen::internal::NormalRandomGenerator<float> prng(seed_);
-        matrix =
-            matrix.random(prng) * (embedding_init_ / sqrtf(embedding_size));
       }
       if (vocab.find(embedding.token()) != vocab.end()) {
         SetNormalizedRow(embedding.vector(), vocab[embedding.token()],
                          embedding_matrix);
       }
     }
+
+    // The vectors file might not contain any embeddings (perhaps due to read
+    // errors), in which case the |embedding_matrix| output is never allocated.
+    // Signal this error early instead of letting downstream ops complain about
+    // a missing input.
+    OP_REQUIRES(
+        context, embedding_matrix != nullptr,
+        InvalidArgument(tensorflow::strings::StrCat(
+            "found no pretrained embeddings in vectors=", vectors_path_,
+            " vocabulary=", vocabulary_path_, " vocab_size=", vocab.size())));
   }
 
  private:
+  // Loads the vocabulary from the task context or vocabulary.
+  tensorflow::Status LoadVocabulary(
+      std::unordered_map<string, int64> *vocabulary) const {
+    if (!task_context_path_.empty()) {
+      return LoadVocabularyFromTaskContext(vocabulary);
+    } else {
+      return LoadVocabularyFromFile(vocabulary);
+    }
+  }
+
+  // Loads the |vocabulary| from the "word-map" input of the task context at
+  // |task_context_path_|, or returns non-OK on error.
+  tensorflow::Status LoadVocabularyFromTaskContext(
+      std::unordered_map<string, int64> *vocabulary) const {
+    vocabulary->clear();
+    string textproto;
+    TF_RETURN_IF_ERROR(ReadFileToString(tensorflow::Env::Default(),
+                                        task_context_path_, &textproto));
+    TaskContext task_context;
+    if (!TextFormat::ParseFromString(textproto, task_context.mutable_spec())) {
+      return InvalidArgument("Could not parse task context at ",
+                             task_context_path_);
+    }
+    const string path =
+        TaskContext::InputFile(*task_context.GetInput("word-map"));
+    const TermFrequencyMap *word_map =
+        SharedStoreUtils::GetWithDefaultName<TermFrequencyMap>(path, 0, 0);
+    for (int i = 0; i < word_map->Size(); ++i) {
+      (*vocabulary)[word_map->GetTerm(i)] = i;
+    }
+    return tensorflow::Status::OK();
+  }
+
+  // Loads the |vocabulary| from the |vocabulary_path_| file, which contains one
+  // word per line in order, or returns non-OK on error.
+  tensorflow::Status LoadVocabularyFromFile(
+      std::unordered_map<string, int64> *vocabulary) const {
+    vocabulary->clear();
+    string text;
+    TF_RETURN_IF_ERROR(
+        ReadFileToString(tensorflow::Env::Default(), vocabulary_path_, &text));
+
+    // Chomp a trailing newline, if any, to avoid producing a spurious empty
+    // term at the end of the vocabulary file.
+    if (!text.empty() && text.back() == '\n') text.pop_back();
+    for (const string &line : tensorflow::str_util::Split(text, "\n")) {
+      if (vocabulary->find(line) != vocabulary->end()) {
+        return InvalidArgument("Vocabulary file at ", vocabulary_path_,
+                               " contains multiple instances of term: ", line);
+      }
+
+      const int64 index = vocabulary->size();
+      (*vocabulary)[line] = index;
+    }
+    return tensorflow::Status::OK();
+  }
+
+  // Allocates the |embedding_matrix| based on the |vocabulary| and |embedding|
+  // and initializes it to random values, or returns non-OK on error.
+  tensorflow::Status InitRandomEmbeddingMatrix(
+      const std::unordered_map<string, int64> &vocabulary,
+      const TokenEmbedding &embedding, OpKernelContext *context,
+      Tensor **embedding_matrix) const {
+    const int rows = vocabulary.size() + num_special_embeddings_;
+    const int columns = embedding.vector().values_size();
+    TF_RETURN_IF_ERROR(context->allocate_output(0, TensorShape({rows, columns}),
+                                                embedding_matrix));
+    auto matrix = (*embedding_matrix)->matrix<float>();
+    Eigen::internal::NormalRandomGenerator<float> prng(seed_);
+    matrix = matrix.random(prng) * (embedding_init_ / sqrtf(columns));
+    return tensorflow::Status::OK();
+  }
+
   // Sets embedding_matrix[row] to a normalized version of the given vector.
   void SetNormalizedRow(const TokenEmbedding::Vector &vector, const int row,
                         Tensor *embedding_matrix) {
@@ -547,8 +627,15 @@ class WordEmbeddingInitializer : public OpKernel {
     }
   }
 
-  // Task context used to configure this op.
-  TaskContext task_context_;
+  // Path to the task context or vocabulary.  Exactly one must be specified.
+  string task_context_path_;
+  string vocabulary_path_;
+
+  // Whether to cache the vectors to a local temp file, to reduce I/O latency.
+  bool cache_vectors_locally_ = true;
+
+  // Number of special embeddings to allocate.
+  int num_special_embeddings_ = 3;
 
   // Seed for random initialization.
   uint64 seed_ = 0;

syntaxnet/syntaxnet/reader_ops_test.py

@@ -15,6 +15,7 @@
 
 """Tests for reader_ops."""
 
+# pylint: disable=no-name-in-module,unused-import,g-bad-import-order,maybe-no-member,no-member,g-importing-member
 
 import os.path
 import numpy as np
@@ -29,7 +30,6 @@ from syntaxnet import graph_builder
 from syntaxnet import sparse_pb2
 from syntaxnet.ops import gen_parser_ops
 
-
 FLAGS = tf.app.flags.FLAGS
 if not hasattr(FLAGS, 'test_srcdir'):
   FLAGS.test_srcdir = ''
@@ -220,6 +220,76 @@ class ParsingReaderOpsTest(test_util.TensorFlowTestCase):
         self.assertEqual(tf.shape(embeddings2)[1].eval(), 3)
         self.assertAllEqual(embeddings1.eval(), embeddings2.eval())
 
+  def testWordEmbeddingInitializerFailIfNeitherTaskContextOrVocabulary(self):
+    with self.test_session():
+      with self.assertRaises(Exception):
+        gen_parser_ops.word_embedding_initializer(vectors='/dev/null').eval()
+
+  def testWordEmbeddingInitializerFailIfBothTaskContextAndVocabulary(self):
+    with self.test_session():
+      with self.assertRaises(Exception):
+        gen_parser_ops.word_embedding_initializer(
+            vectors='/dev/null',
+            task_context='/dev/null',
+            vocabulary='/dev/null').eval()
+
+  def testWordEmbeddingInitializerVocabularyFile(self):
+    records_path = os.path.join(FLAGS.test_tmpdir, 'records3')
+    writer = tf.python_io.TFRecordWriter(records_path)
+    writer.write(self._token_embedding('a', [1, 2, 3]))
+    writer.write(self._token_embedding('b', [2, 3, 4]))
+    writer.write(self._token_embedding('c', [3, 4, 5]))
+    writer.write(self._token_embedding('d', [4, 5, 6]))
+    writer.write(self._token_embedding('e', [5, 6, 7]))
+    del writer
+
+    vocabulary_path = os.path.join(FLAGS.test_tmpdir, 'vocabulary3')
+    with open(vocabulary_path, 'w') as vocabulary_file:
+      vocabulary_file.write('a\nc\ne\nx\n')  # 'x' not in pretrained embeddings
+
+    # Enumerate a variety of configurations.
+    for cache_vectors_locally in [False, True]:
+      for num_special_embeddings in [None, 1, 2, 5]:  # None = use default of 3
+        with self.test_session():
+          embeddings = gen_parser_ops.word_embedding_initializer(
+              vectors=records_path,
+              vocabulary=vocabulary_path,
+              cache_vectors_locally=cache_vectors_locally,
+              num_special_embeddings=num_special_embeddings)
+
+          # Expect 4 embeddings from the vocabulary plus special embeddings.
+          expected_num_embeddings = 4 + (num_special_embeddings or 3)
+          self.assertAllEqual([expected_num_embeddings, 3],
+                              tf.shape(embeddings).eval())
+
+          # The first 3 embeddings should be pretrained.
+          norm_a = (1.0 + 4.0 + 9.0) ** 0.5
+          norm_c = (9.0 + 16.0 + 25.0) ** 0.5
+          norm_e = (25.0 + 36.0 + 49.0) ** 0.5
+          self.assertAllClose([[1.0 / norm_a, 2.0 / norm_a, 3.0 / norm_a],
+                               [3.0 / norm_c, 4.0 / norm_c, 5.0 / norm_c],
+                               [5.0 / norm_e, 6.0 / norm_e, 7.0 / norm_e]],
+                              embeddings[:3].eval())
+
+  def testWordEmbeddingInitializerVocabularyFileWithDuplicates(self):
+    records_path = os.path.join(FLAGS.test_tmpdir, 'records4')
+    writer = tf.python_io.TFRecordWriter(records_path)
+    writer.write(self._token_embedding('a', [1, 2, 3]))
+    writer.write(self._token_embedding('b', [2, 3, 4]))
+    writer.write(self._token_embedding('c', [3, 4, 5]))
+    writer.write(self._token_embedding('d', [4, 5, 6]))
+    writer.write(self._token_embedding('e', [5, 6, 7]))
+    del writer
+
+    vocabulary_path = os.path.join(FLAGS.test_tmpdir, 'vocabulary4')
+    with open(vocabulary_path, 'w') as vocabulary_file:
+      vocabulary_file.write('a\nc\ne\nx\ny\nx')  # 'x' duplicated
+
+    with self.test_session():
+      with self.assertRaises(Exception):
+        gen_parser_ops.word_embedding_initializer(
+            vectors=records_path, vocabulary=vocabulary_path).eval()
+
 
 if __name__ == '__main__':
   googletest.main()

syntaxnet/syntaxnet/syntaxnet_ops.py

+# Copyright 2017 Google Inc. 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.
+# ==============================================================================
+
+"""Imports the SyntaxNet ops and their C++ implementations."""
+
+
+from syntaxnet.ops.gen_parser_ops import *  # pylint: disable=wildcard-import
+
+import syntaxnet.load_parser_ops