AhoCorasickTrie: Fast Searching for Multiple Keywords in Multiple Texts
Aho-Corasick is an optimal algorithm for finding many
keywords in a text. It can locate all matches in a text in O(N+M) time; i.e.,
the time needed scales linearly with the number of keywords (N) and the size of
the text (M). Compare this to the naive approach which takes O(N*M) time to loop
through each pattern and scan for it in the text. This implementation builds the
trie (the generic name of the data structure) and runs the search in a single
function call. If you want to search multiple texts with the same trie, the
function will take a list or vector of texts and return a list of matches to
each text. By default, all 128 ASCII characters are allowed in both the keywords
and the text. A more efficient trie is possible if the alphabet size can be
reduced. For example, DNA sequences use at most 19 distinct characters and
usually only 4; protein sequences use at most 26 distinct characters and usually
only 20. UTF-8 (Unicode) matching is not currently supported.
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