Multimatcher is an implementation of the Aho-Corasick (Aho & Corasick 1975) search algorithm. It efficiently finds multiple keywords in an input string, without having to loop over the input string multiple times.
The rationale behind the Multimatcher is that most often we want to do something with the found matches, and the Multimatcher provides a flexible "replace" method that allows different use cases such as:
- find and delete
- find and replace
- tag with a global label (i.e. all matches get the same label)
- tag with custom label (i.e. each match gets its own label)
- count matches
When possible, it's recommended to set whole_words_only to True, which makes matching significantly faster.
from multimatcher import Multimatcher
mm = Multimatcher(separator=' ')
mm.set_replacement_text("") # matches will be deleted
mm.set_search_patterns(['a', 'b', 'c'])
mm.replace("x a y b z c") # produces "x y z"
from multimatcher import Multimatcher
mm = Multimatcher(separator=' ')
mm.set_replacement_method(lambda x: x.capitalize()) # matches will be capitalized
mm.set_search_patterns(['a', 'b', 'c'])
mm.replace("x a y b z c") # produces "x A y B z C"
from multimatcher import Multimatcher
mm = Multimatcher(separator=' ')
mm.set_replacement_text("0") # all matches will be replaced with 0
mm.set_search_patterns(['a', 'b', 'c'])
mm.replace("x a y b z c") # produces "x 0 y 0 z 0"
from multimatcher import Multimatcher
mm = Multimatcher(separator=' ')
mm.set_replacement_map({"a": "1", "b": "2", "c": "3"}) # replaces a > 1, b > 2, c > 3
mm.set_search_patterns(['a', 'b', 'c'])
mm.replace("x a y b z c") # produces "x 1 y 2 z 3"
from multimatcher import Multimatcher
mm = Multimatcher(separator='')
mm.set_search_patterns(['a', 'b', 'c'])
mm.count("aa xx bb yy cc zz") # produces {'a': 2, 'b': 2, 'c': 2}
Aho, A. V., & Corasick, M. J. (1975). Efficient string matching: an aid to bibliographic search. Communications of the ACM, 18(6), 333-340.