Table 8.

Top 15 n-gram features from feature sets 1 and 2

Rank	Feature set 1: Bag of words	Feature set 2: n-grams
1	ii	nyha class ii
2	iii	class ii
3	iv	nyha class iii
4	b	class iii
5	428.0dd	nyha class iv
6	428.0db	class iv
7	chf	nyha class ii
8	congestive	nyha class 2
9	428.0 dc	nyha class 3
10	lvad	class
11	systolic	chf
12	diastolic	class 3
13	428.0bm	class 2
14	c	congestive heart failure
15	stage	nyha class