Discovering and visualizing indirect associations between biomedical concepts

doi:10.1093/bioinformatics/btr214

From:

Bioinformatics. 2011 July 1; 27(13): i111–i119.

Published online 2011 June 14. doi: 10.1093/bioinformatics/btr214

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Table 3.

Feature templates used in the CRF tagger

Word unigram	w_i−5, w_i−4, w_i−3, w_i−2, w_i−1, w_iw_i+1, w_i+2, w_i+3, w_i+4, w_i+5	& y_i
Word bigram	w_i−1w_i, w_iw_i+1	& y_i
Word trigram	w_i−1w_iw_i+1	& y_i
Substrings	substrings of w_i	& y_i
	(up to length 10)
Word shape	S(w_i)	& y_i
Tag bigram	True	& y_i−1y_i

w_i is the current word. y_i is the current tag. Word shape S(w_i) is produced by converting capital letters into ‘A’, small letters into ‘a’ and numerals into ‘#’.

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