Source code for

"""Tree-structured data.

    - Stanford Sentiment Treebank
from __future__ import absolute_import

from collections import namedtuple, OrderedDict
import networkx as nx

import numpy as np
import os

from .. import backend as F
from ..graph import DGLGraph
from .utils import download, extract_archive, get_download_dir, _get_dgl_url

__all__ = ['SSTBatch', 'SST']

_urls = {
    'sst' : 'dataset/',

SSTBatch = namedtuple('SSTBatch', ['graph', 'mask', 'wordid', 'label'])

[docs]class SST(object): """Stanford Sentiment Treebank dataset. Each sample is the constituency tree of a sentence. The leaf nodes represent words. The word is a int value stored in the ``x`` feature field. The non-leaf node has a special value ``PAD_WORD`` in the ``x`` field. Each node also has a sentiment annotation: 5 classes (very negative, negative, neutral, positive and very positive). The sentiment label is a int value stored in the ``y`` feature field. .. note:: This dataset class is compatible with pytorch's :class:`Dataset` class. .. note:: All the samples will be loaded and preprocessed in the memory first. Parameters ---------- mode : str, optional Can be ``'train'``, ``'val'``, ``'test'`` and specifies which data file to use. vocab_file : str, optional Optional vocabulary file. """ PAD_WORD=-1 # special pad word id UNK_WORD=-1 # out-of-vocabulary word id def __init__(self, mode='train', vocab_file=None): self.mode = mode self.dir = get_download_dir() self.zip_file_path='{}/'.format(self.dir) self.pretrained_file = 'glove.840B.300d.txt' if mode == 'train' else '' self.pretrained_emb = None self.vocab_file = '{}/sst/vocab.txt'.format(self.dir) if vocab_file is None else vocab_file download(_get_dgl_url(_urls['sst']), path=self.zip_file_path) extract_archive(self.zip_file_path, '{}/sst'.format(self.dir)) self.trees = [] self.num_classes = 5 print('Preprocessing...') self._load() print('Dataset creation finished. #Trees:', len(self.trees)) def _load(self): from nltk.corpus.reader import BracketParseCorpusReader # load vocab file self.vocab = OrderedDict() with open(self.vocab_file, encoding='utf-8') as vf: for line in vf.readlines(): line = line.strip() self.vocab[line] = len(self.vocab) # filter glove if self.pretrained_file != '' and os.path.exists(self.pretrained_file): glove_emb = {} with open(self.pretrained_file, 'r', encoding='utf-8') as pf: for line in pf.readlines(): sp = line.split(' ') if sp[0].lower() in self.vocab: glove_emb[sp[0].lower()] = np.asarray([float(x) for x in sp[1:]]) files = ['{}.txt'.format(self.mode)] corpus = BracketParseCorpusReader('{}/sst'.format(self.dir), files) sents = corpus.parsed_sents(files[0]) #initialize with glove pretrained_emb = [] fail_cnt = 0 for line in self.vocab.keys(): if self.pretrained_file != '' and os.path.exists(self.pretrained_file): if not line.lower() in glove_emb: fail_cnt += 1 pretrained_emb.append(glove_emb.get(line.lower(), np.random.uniform(-0.05, 0.05, 300))) if self.pretrained_file != '' and os.path.exists(self.pretrained_file): self.pretrained_emb = F.tensor(np.stack(pretrained_emb, 0)) print('Miss word in GloVe {0:.4f}'.format(1.0*fail_cnt/len(self.pretrained_emb))) # build trees for sent in sents: self.trees.append(self._build_tree(sent)) def _build_tree(self, root): g = nx.DiGraph() def _rec_build(nid, node): for child in node: cid = g.number_of_nodes() if isinstance(child[0], str) or isinstance(child[0], bytes): # leaf node word = self.vocab.get(child[0].lower(), self.UNK_WORD) g.add_node(cid, x=word, y=int(child.label()), mask=1) else: g.add_node(cid, x=SST.PAD_WORD, y=int(child.label()), mask=0) _rec_build(cid, child) g.add_edge(cid, nid) # add root g.add_node(0, x=SST.PAD_WORD, y=int(root.label()), mask=0) _rec_build(0, root) ret = DGLGraph() ret.from_networkx(g, node_attrs=['x', 'y', 'mask']) return ret
[docs] def __getitem__(self, idx): """Get the tree with index idx. Parameters ---------- idx : int Tree index. Returns ------- dgl.DGLGraph Tree. """ return self.trees[idx]
[docs] def __len__(self): """Get the number of trees in the dataset. Returns ------- int Number of trees. """ return len(self.trees)
@property def num_vocabs(self): return len(self.vocab)