R: Cut behaves strangely when converted to numeric

Question

Some example code first:

Scores = c(5,4,3,2,1)
Breaks = c(0,0.6,0.8,1,1.2,100)
cut(1.19,breaks=Breaks, labels=Scores)
as.numeric(cut(1.19,breaks=Breaks,labels=Scores)

The first Output ist correctly 2, the second is wrong with 4. Why is there this difference? I actually need a numeric value, but the correct one...so how do I convert it correctly?

score 4 · Accepted Answer · answered Dec 17 '13 at 11:56

4

cut returns a factor and 2 is the 4th factor level. You need to convert factors to character first if you want the level labels as numerics:

as.numeric(as.character(cut(1.19,breaks=Breaks,labels=Scores)))
[1] 2

answered Dec 17 '13 at 11:56

James

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I obivously still don't really understand this factor type. But it works like a charm, thx :) – MichiZH Dec 17 '13 at 12:04

score 1 · Answer 2 · answered Dec 17 '13 at 12:17

1

You need to get the levels of the factor out for each element. Try:

f <- cut(1.19,breaks=Breaks,labels=Scores)
as.numeric( levels(f)[f] )

(While James' answer works fine too this might help you a bit with understanding the factor)

answered Dec 17 '13 at 12:17

John

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R: Cut behaves strangely when converted to numeric

2 Answers2