BIST Dependency Parser¶
Graph-based dependency parser using BiLSTM feature extractors¶
The techniques behind the parser are described in the Simple and Accurate Dependency Parsing Using Bidirectional LSTM Feature Representations .
To use the module, import it like so:
from nlp_architect.models.bist_parser import BISTModel
Training the parser requires having a
formatted according to the CoNLL-U data format,
annotated with part-of-speech tags and dependencies.
The benchmark was performed on a Mac book pro with i7 processor. The parser achieves
an accuracy of 93.8 UAS on the standard Penn Treebank dataset (Universal Dependencies).
To train a parsing model with default parameters, type the following:
parser = BISTModel() parser.fit('/path/to/train.conllu')
Optionally, the following model/training parameters can be supplied (overriding their default values listed below):
parser = BISTModel(activation='tanh', lstm_layers=2, lstm_dims=125, pos_dims=25) parser.fit('/path/to/train.conllu', epochs=10)
Conducting Intermediate Evaluations¶
If a path to a development dataset file (annotated with POS tags and dependencies) is supplied, intermediate model evaluations are conducted:
parser = BISTModel() parser.fit('/path/to/train.conllu', dev='/path/to/dev.conllu')
For each completed epoch, denoted by n, the following files will be created in the dataset’s directory:
- dev_epoch_n_pred.conllu - prediction results on dev file after n iterations.
- dev_epoch_n_pred_eval.txt - accuracy results of the above predictions.
Once you have a trained
BISTModel, there are two acceptable input modes for running inference
with it. For both modes, the input must be annotated with part-of-speech tags.
File Input Mode¶
Supply a path to a dataset file in the CoNLL-U data format.
predictions = parser.predict(dataset='/path/to/test.conllu')
ConllEntry Input Mode¶
Supply a list of sentences, where each sentence is a list of annotated tokens, represented by
predictions = parser.predict(conll='/path/to/test.conllu')
The output format is the same as in file input mode.
Running an evaluation requires the following: - Inference must be run in file input mode - The input file must be annotated with dependencies as well
To evaluate predictions immediately after they’re generated, type the following:
predictions = parser.predict(dataset='/path/to/test.conllu', evaluate=True)
This will produce 2 files in your input dataset’s directory:
- test_pred.conllu - predictions file in CoNLL-U format
- test_pred_eval.txt - evaluation report text file
Saving and Loading a Model¶
To save a
BISTModel to some path, type:
This operation will also produce a model parameters file named params.json, in the same directory. This file is required for loading the model afterwards.
To load a
BISTModel from some path, type:
Note that this operation will also look for the params.json in the same directory.
|||Kiperwasser, E., & Goldberg, Y. (2016). Simple and Accurate Dependency Parsing Using Bidirectional LSTM Feature Representations. Transactions Of The Association For Computational Linguistics, 4, 313-327. https://transacl.org/ojs/index.php/tacl/article/view/885/198|