"""
A set of utilities for dealing with pyconll defined types. This is simply a
collection of functions.
"""
import itertools
[docs]def find_ngrams(conll, ngram, case_sensitive=True):
"""
Find the occurences of the ngram in the provided Conll collection.
This method returns every sentence along with the token position in the
sentence that starts the ngram. The matching algorithm does not currently
account for multiword tokens, so "don't" should be separated into "do" and
"not" in the input.
Args:
sentence: The sentence in which to search for the ngram.
ngram: The ngram to search for. A random access iterator.
case_sensitive: Flag to indicate if the ngram search should be case
sensitive.
Returns:
An iterator over the ngrams in the Conll object. The first element is
the sentence and the second element is the numeric token index.
"""
for sentence in conll:
i = 0
while i < len(sentence):
token = sentence[i]
cased_form, cased_ngram_start = _get_cased(case_sensitive,
token.form, ngram[0])
if cased_form == cased_ngram_start and not token.is_multiword():
matches = True
multiword_token_offset = 0
for j, ngram_token in enumerate(
itertools.islice(ngram, 1, None)):
new_token = sentence[i + j + multiword_token_offset + 1]
if new_token.is_multiword():
multiword_token_offset += 1
new_token = sentence[i + j + multiword_token_offset +
1]
if new_token.form != ngram_token:
matches = False
break
if matches:
yield (sentence, i)
i += 1
def _get_cased(case_sensitive, *args):
"""
Get the cased versions of the provided strings if applicable.
Args:
case_sensitive: If False, then returns lowercase versions of all
strings.
args: The strings to get appropriately cased versions of.
Returns:
A list of case converted strings as necessary.
"""
if not case_sensitive:
args = map(lambda s: s.lower(), args)
return args