[R] Factoring a variable

Erik Iverson eriki at ccbr.umn.edu
Thu Jun 17 21:53:32 CEST 2010

Noah Silverman wrote:
> Hi,
> I have a dataset where the results are coded ("yes", "no")  We want to
> do some machine learning with SVM to predict the "yes" outcome
> My problem is that if I just use the as.factor function to convert, then
> it reverses the levels.
> ----------------------
> x <- c("no", "no", "no", "yes", "yes", "no", "no")
>  as.factor(x)
> [1] no  no  no  yes yes no  no
> Levels: no yes

You want to use ?factor, not ?as.factor.  Then you can use the "levels" 

factor(x, levels = c("yes", "no"))

Also see ?relevel.

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