The purpose of the module Match is to get the offsets (as well as the string between those offsets, for debugging) of a cleaned-up, tokenized string from its original, untokenized source. “Big deal,” you might say, but this is actually a pretty difficult task if the original text is sufficiently messy, not to mention rife with Unicode characters.
Consider some text, stored in a variable original_text, like:
I am writing a letter ! Sometimes,I forget to put spaces (and do weird stuff with punctuation) ? J'aurai une pomme, s'il vous plâit !This will/should/might be properly tokenized as:
[['I', 'am', 'writing', 'a', 'letter', '!'],
['Sometimes', ',', 'I', 'forget', 'to', 'put', 'spaces', '-LRB-', 'and', 'do', 'weird', 'stuff', 'with', 'punctuation', '-RRB-', '?'],
["J'aurai", 'une', 'pomme', ',', "s'il", 'vous', 'plâit', '!']]Now:
In [2]: import match
In [3]: match.match(original_text, ['-LRB-', 'and', 'do', 'weird', 'stuff', 'with', 'punctuation', '-RRB-'])
Out[3]: [(60, 97, '(and do weird stuff with punctuation)')]
In [4]: match.match(original_text, ['I', 'am', 'writing', 'a', 'letter', '!'])
Out[4]: [(0, 25, 'I am writing a letter !')]
In [5]: match.match(original_text, ["s'il", 'vous', 'plâit', '!'])
Out[5]: [(121, 138, "s'il vous plâit !")]The return type from match() is a list because it will return all occurrences of the argument, be it a list of tokens or a single string (word):
In [6]: match.match(original_text, "I")
Out[6]: [(0, 1, 'I'), (37, 38, 'I')]When passing in a single string, match() is expecting that string to be a single word or token. Thus:
In [7]: match.match("****because,the****", "because , the")
Out[7]: []Try passing in "because , the".split(' ') instead, or better yet, the output from a proper tokenizer.
For convenience, a function called match_lines() is provided:
In [8]: match.match_lines(original_text, [
...: ['-LRB-', 'and', 'do', 'weird', 'stuff', 'with', 'punctuation', '-RRB-'],
...: ['I', 'am', 'writing', 'a', 'letter', '!'],
...: "I"
...: ])
Out[8]:
[(0, 1, 'I'),
(0, 25, 'I am writing a letter !'),
(37, 38, 'I'),
(60, 97, '(and do weird stuff with punctuation)')]The values returned will always be sorted by their offsets.
pip install match or conda install -c ets match