Source code for nltk.corpus.reader.conll

# Natural Language Toolkit: CONLL Corpus Reader
#
# Copyright (C) 2001-2021 NLTK Project
# Author: Steven Bird <stevenbird1@gmail.com>
#         Edward Loper <edloper@gmail.com>
# URL: <https://www.nltk.org/>
# For license information, see LICENSE.TXT

"""
Read CoNLL-style chunk fileids.
"""

import textwrap

from nltk.corpus.reader.api import *
from nltk.corpus.reader.util import *
from nltk.tag import map_tag
from nltk.tree import Tree
from nltk.util import LazyConcatenation, LazyMap


[docs]class ConllCorpusReader(CorpusReader): """ A corpus reader for CoNLL-style files. These files consist of a series of sentences, separated by blank lines. Each sentence is encoded using a table (or "grid") of values, where each line corresponds to a single word, and each column corresponds to an annotation type. The set of columns used by CoNLL-style files can vary from corpus to corpus; the ``ConllCorpusReader`` constructor therefore takes an argument, ``columntypes``, which is used to specify the columns that are used by a given corpus. By default columns are split by consecutive whitespaces, with the ``separator`` argument you can set a string to split by (e.g. ``\'\t\'``). @todo: Add support for reading from corpora where different parallel files contain different columns. @todo: Possibly add caching of the grid corpus view? This would allow the same grid view to be used by different data access methods (eg words() and parsed_sents() could both share the same grid corpus view object). @todo: Better support for -DOCSTART-. Currently, we just ignore it, but it could be used to define methods that retrieve a document at a time (eg parsed_documents()). """ # ///////////////////////////////////////////////////////////////// # Column Types # ///////////////////////////////////////////////////////////////// WORDS = "words" #: column type for words POS = "pos" #: column type for part-of-speech tags TREE = "tree" #: column type for parse trees CHUNK = "chunk" #: column type for chunk structures NE = "ne" #: column type for named entities SRL = "srl" #: column type for semantic role labels IGNORE = "ignore" #: column type for column that should be ignored #: A list of all column types supported by the conll corpus reader. COLUMN_TYPES = (WORDS, POS, TREE, CHUNK, NE, SRL, IGNORE) # ///////////////////////////////////////////////////////////////// # Constructor # /////////////////////////////////////////////////////////////////
[docs] def __init__( self, root, fileids, columntypes, chunk_types=None, root_label="S", pos_in_tree=False, srl_includes_roleset=True, encoding="utf8", tree_class=Tree, tagset=None, separator=None, ): for columntype in columntypes: if columntype not in self.COLUMN_TYPES: raise ValueError("Bad column type %r" % columntype) if isinstance(chunk_types, str): chunk_types = [chunk_types] self._chunk_types = chunk_types self._colmap = {c: i for (i, c) in enumerate(columntypes)} self._pos_in_tree = pos_in_tree self._root_label = root_label # for chunks self._srl_includes_roleset = srl_includes_roleset self._tree_class = tree_class CorpusReader.__init__(self, root, fileids, encoding) self._tagset = tagset self.sep = separator
# ///////////////////////////////////////////////////////////////// # Data Access Methods # /////////////////////////////////////////////////////////////////
[docs] def words(self, fileids=None): self._require(self.WORDS) return LazyConcatenation(LazyMap(self._get_words, self._grids(fileids)))
[docs] def sents(self, fileids=None): self._require(self.WORDS) return LazyMap(self._get_words, self._grids(fileids))
[docs] def tagged_words(self, fileids=None, tagset=None): self._require(self.WORDS, self.POS) def get_tagged_words(grid): return self._get_tagged_words(grid, tagset) return LazyConcatenation(LazyMap(get_tagged_words, self._grids(fileids)))
[docs] def tagged_sents(self, fileids=None, tagset=None): self._require(self.WORDS, self.POS) def get_tagged_words(grid): return self._get_tagged_words(grid, tagset) return LazyMap(get_tagged_words, self._grids(fileids))
[docs] def chunked_words(self, fileids=None, chunk_types=None, tagset=None): self._require(self.WORDS, self.POS, self.CHUNK) if chunk_types is None: chunk_types = self._chunk_types def get_chunked_words(grid): # capture chunk_types as local var return self._get_chunked_words(grid, chunk_types, tagset) return LazyConcatenation(LazyMap(get_chunked_words, self._grids(fileids)))
[docs] def chunked_sents(self, fileids=None, chunk_types=None, tagset=None): self._require(self.WORDS, self.POS, self.CHUNK) if chunk_types is None: chunk_types = self._chunk_types def get_chunked_words(grid): # capture chunk_types as local var return self._get_chunked_words(grid, chunk_types, tagset) return LazyMap(get_chunked_words, self._grids(fileids))
[docs] def parsed_sents(self, fileids=None, pos_in_tree=None, tagset=None): self._require(self.WORDS, self.POS, self.TREE) if pos_in_tree is None: pos_in_tree = self._pos_in_tree def get_parsed_sent(grid): # capture pos_in_tree as local var return self._get_parsed_sent(grid, pos_in_tree, tagset) return LazyMap(get_parsed_sent, self._grids(fileids))
[docs] def srl_spans(self, fileids=None): self._require(self.SRL) return LazyMap(self._get_srl_spans, self._grids(fileids))
[docs] def srl_instances(self, fileids=None, pos_in_tree=None, flatten=True): self._require(self.WORDS, self.POS, self.TREE, self.SRL) if pos_in_tree is None: pos_in_tree = self._pos_in_tree def get_srl_instances(grid): # capture pos_in_tree as local var return self._get_srl_instances(grid, pos_in_tree) result = LazyMap(get_srl_instances, self._grids(fileids)) if flatten: result = LazyConcatenation(result) return result
[docs] def iob_words(self, fileids=None, tagset=None): """ :return: a list of word/tag/IOB tuples :rtype: list(tuple) :param fileids: the list of fileids that make up this corpus :type fileids: None or str or list """ self._require(self.WORDS, self.POS, self.CHUNK) def get_iob_words(grid): return self._get_iob_words(grid, tagset) return LazyConcatenation(LazyMap(get_iob_words, self._grids(fileids)))
[docs] def iob_sents(self, fileids=None, tagset=None): """ :return: a list of lists of word/tag/IOB tuples :rtype: list(list) :param fileids: the list of fileids that make up this corpus :type fileids: None or str or list """ self._require(self.WORDS, self.POS, self.CHUNK) def get_iob_words(grid): return self._get_iob_words(grid, tagset) return LazyMap(get_iob_words, self._grids(fileids))
# ///////////////////////////////////////////////////////////////// # Grid Reading # ///////////////////////////////////////////////////////////////// def _grids(self, fileids=None): # n.b.: we could cache the object returned here (keyed on # fileids), which would let us reuse the same corpus view for # different things (eg srl and parse trees). return concat( [ StreamBackedCorpusView(fileid, self._read_grid_block, encoding=enc) for (fileid, enc) in self.abspaths(fileids, True) ] ) def _read_grid_block(self, stream): grids = [] for block in read_blankline_block(stream): block = block.strip() if not block: continue grid = [line.split(self.sep) for line in block.split("\n")] # If there's a docstart row, then discard. ([xx] eventually it # would be good to actually use it) if grid[0][self._colmap.get("words", 0)] == "-DOCSTART-": del grid[0] # Check that the grid is consistent. for row in grid: if len(row) != len(grid[0]): raise ValueError("Inconsistent number of columns:\n%s" % block) grids.append(grid) return grids # ///////////////////////////////////////////////////////////////// # Transforms # ///////////////////////////////////////////////////////////////// # given a grid, transform it into some representation (e.g., # a list of words or a parse tree). def _get_words(self, grid): return self._get_column(grid, self._colmap["words"]) def _get_tagged_words(self, grid, tagset=None): pos_tags = self._get_column(grid, self._colmap["pos"]) if tagset and tagset != self._tagset: pos_tags = [map_tag(self._tagset, tagset, t) for t in pos_tags] return list(zip(self._get_column(grid, self._colmap["words"]), pos_tags)) def _get_iob_words(self, grid, tagset=None): pos_tags = self._get_column(grid, self._colmap["pos"]) if tagset and tagset != self._tagset: pos_tags = [map_tag(self._tagset, tagset, t) for t in pos_tags] return list( zip( self._get_column(grid, self._colmap["words"]), pos_tags, self._get_column(grid, self._colmap["chunk"]), ) ) def _get_chunked_words(self, grid, chunk_types, tagset=None): # n.b.: this method is very similar to conllstr2tree. words = self._get_column(grid, self._colmap["words"]) pos_tags = self._get_column(grid, self._colmap["pos"]) if tagset and tagset != self._tagset: pos_tags = [map_tag(self._tagset, tagset, t) for t in pos_tags] chunk_tags = self._get_column(grid, self._colmap["chunk"]) stack = [Tree(self._root_label, [])] for (word, pos_tag, chunk_tag) in zip(words, pos_tags, chunk_tags): if chunk_tag == "O": state, chunk_type = "O", "" else: (state, chunk_type) = chunk_tag.split("-") # If it's a chunk we don't care about, treat it as O. if chunk_types is not None and chunk_type not in chunk_types: state = "O" # Treat a mismatching I like a B. if state == "I" and chunk_type != stack[-1].label(): state = "B" # For B or I: close any open chunks if state in "BO" and len(stack) == 2: stack.pop() # For B: start a new chunk. if state == "B": new_chunk = Tree(chunk_type, []) stack[-1].append(new_chunk) stack.append(new_chunk) # Add the word token. stack[-1].append((word, pos_tag)) return stack[0] def _get_parsed_sent(self, grid, pos_in_tree, tagset=None): words = self._get_column(grid, self._colmap["words"]) pos_tags = self._get_column(grid, self._colmap["pos"]) if tagset and tagset != self._tagset: pos_tags = [map_tag(self._tagset, tagset, t) for t in pos_tags] parse_tags = self._get_column(grid, self._colmap["tree"]) treestr = "" for (word, pos_tag, parse_tag) in zip(words, pos_tags, parse_tags): if word == "(": word = "-LRB-" if word == ")": word = "-RRB-" if pos_tag == "(": pos_tag = "-LRB-" if pos_tag == ")": pos_tag = "-RRB-" (left, right) = parse_tag.split("*") right = right.count(")") * ")" # only keep ')'. treestr += f"{left} ({pos_tag} {word}) {right}" try: tree = self._tree_class.fromstring(treestr) except (ValueError, IndexError): tree = self._tree_class.fromstring(f"({self._root_label} {treestr})") if not pos_in_tree: for subtree in tree.subtrees(): for i, child in enumerate(subtree): if ( isinstance(child, Tree) and len(child) == 1 and isinstance(child[0], str) ): subtree[i] = (child[0], child.label()) return tree def _get_srl_spans(self, grid): """ list of list of (start, end), tag) tuples """ if self._srl_includes_roleset: predicates = self._get_column(grid, self._colmap["srl"] + 1) start_col = self._colmap["srl"] + 2 else: predicates = self._get_column(grid, self._colmap["srl"]) start_col = self._colmap["srl"] + 1 # Count how many predicates there are. This tells us how many # columns to expect for SRL data. num_preds = len([p for p in predicates if p != "-"]) spanlists = [] for i in range(num_preds): col = self._get_column(grid, start_col + i) spanlist = [] stack = [] for wordnum, srl_tag in enumerate(col): (left, right) = srl_tag.split("*") for tag in left.split("("): if tag: stack.append((tag, wordnum)) for i in range(right.count(")")): (tag, start) = stack.pop() spanlist.append(((start, wordnum + 1), tag)) spanlists.append(spanlist) return spanlists def _get_srl_instances(self, grid, pos_in_tree): tree = self._get_parsed_sent(grid, pos_in_tree) spanlists = self._get_srl_spans(grid) if self._srl_includes_roleset: predicates = self._get_column(grid, self._colmap["srl"] + 1) rolesets = self._get_column(grid, self._colmap["srl"]) else: predicates = self._get_column(grid, self._colmap["srl"]) rolesets = [None] * len(predicates) instances = ConllSRLInstanceList(tree) for wordnum, predicate in enumerate(predicates): if predicate == "-": continue # Decide which spanlist to use. Don't assume that they're # sorted in the same order as the predicates (even though # they usually are). for spanlist in spanlists: for (start, end), tag in spanlist: if wordnum in range(start, end) and tag in ("V", "C-V"): break else: continue break else: raise ValueError("No srl column found for %r" % predicate) instances.append( ConllSRLInstance(tree, wordnum, predicate, rolesets[wordnum], spanlist) ) return instances # ///////////////////////////////////////////////////////////////// # Helper Methods # ///////////////////////////////////////////////////////////////// def _require(self, *columntypes): for columntype in columntypes: if columntype not in self._colmap: raise ValueError( "This corpus does not contain a %s " "column." % columntype ) @staticmethod def _get_column(grid, column_index): return [grid[i][column_index] for i in range(len(grid))]
[docs]class ConllSRLInstance: """ An SRL instance from a CoNLL corpus, which identifies and providing labels for the arguments of a single verb. """ # [xx] add inst.core_arguments, inst.argm_arguments?
[docs] def __init__(self, tree, verb_head, verb_stem, roleset, tagged_spans): self.verb = [] """A list of the word indices of the words that compose the verb whose arguments are identified by this instance. This will contain multiple word indices when multi-word verbs are used (e.g. 'turn on').""" self.verb_head = verb_head """The word index of the head word of the verb whose arguments are identified by this instance. E.g., for a sentence that uses the verb 'turn on,' ``verb_head`` will be the word index of the word 'turn'.""" self.verb_stem = verb_stem self.roleset = roleset self.arguments = [] """A list of ``(argspan, argid)`` tuples, specifying the location and type for each of the arguments identified by this instance. ``argspan`` is a tuple ``start, end``, indicating that the argument consists of the ``words[start:end]``.""" self.tagged_spans = tagged_spans """A list of ``(span, id)`` tuples, specifying the location and type for each of the arguments, as well as the verb pieces, that make up this instance.""" self.tree = tree """The parse tree for the sentence containing this instance.""" self.words = tree.leaves() """A list of the words in the sentence containing this instance.""" # Fill in the self.verb and self.arguments values. for (start, end), tag in tagged_spans: if tag in ("V", "C-V"): self.verb += list(range(start, end)) else: self.arguments.append(((start, end), tag))
def __repr__(self): # Originally, its: ##plural = 's' if len(self.arguments) != 1 else '' plural = "s" if len(self.arguments) != 1 else "" return "<ConllSRLInstance for %r with %d argument%s>" % ( (self.verb_stem, len(self.arguments), plural) )
[docs] def pprint(self): verbstr = " ".join(self.words[i][0] for i in self.verb) hdr = f"SRL for {verbstr!r} (stem={self.verb_stem!r}):\n" s = "" for i, word in enumerate(self.words): if isinstance(word, tuple): word = word[0] for (start, end), argid in self.arguments: if i == start: s += "[%s " % argid if i == end: s += "] " if i in self.verb: word = "<<%s>>" % word s += word + " " return hdr + textwrap.fill( s.replace(" ]", "]"), initial_indent=" ", subsequent_indent=" " )
[docs]class ConllSRLInstanceList(list): """ Set of instances for a single sentence """
[docs] def __init__(self, tree, instances=()): self.tree = tree list.__init__(self, instances)
def __str__(self): return self.pprint()
[docs] def pprint(self, include_tree=False): # Sanity check: trees should be the same for inst in self: if inst.tree != self.tree: raise ValueError("Tree mismatch!") # If desired, add trees: if include_tree: words = self.tree.leaves() pos = [None] * len(words) synt = ["*"] * len(words) self._tree2conll(self.tree, 0, words, pos, synt) s = "" for i in range(len(words)): # optional tree columns if include_tree: s += "%-20s " % words[i] s += "%-8s " % pos[i] s += "%15s*%-8s " % tuple(synt[i].split("*")) # verb head column for inst in self: if i == inst.verb_head: s += "%-20s " % inst.verb_stem break else: s += "%-20s " % "-" # Remaining columns: self for inst in self: argstr = "*" for (start, end), argid in inst.tagged_spans: if i == start: argstr = f"({argid}{argstr}" if i == (end - 1): argstr += ")" s += "%-12s " % argstr s += "\n" return s
def _tree2conll(self, tree, wordnum, words, pos, synt): assert isinstance(tree, Tree) if len(tree) == 1 and isinstance(tree[0], str): pos[wordnum] = tree.label() assert words[wordnum] == tree[0] return wordnum + 1 elif len(tree) == 1 and isinstance(tree[0], tuple): assert len(tree[0]) == 2 pos[wordnum], pos[wordnum] = tree[0] return wordnum + 1 else: synt[wordnum] = f"({tree.label()}{synt[wordnum]}" for child in tree: wordnum = self._tree2conll(child, wordnum, words, pos, synt) synt[wordnum - 1] += ")" return wordnum
[docs]class ConllChunkCorpusReader(ConllCorpusReader): """ A ConllCorpusReader whose data file contains three columns: words, pos, and chunk. """
[docs] def __init__( self, root, fileids, chunk_types, encoding="utf8", tagset=None, separator=None ): ConllCorpusReader.__init__( self, root, fileids, ("words", "pos", "chunk"), chunk_types=chunk_types, encoding=encoding, tagset=tagset, separator=separator, )