[R] switch and factors

From: baptiste auguie <baptiste.auguie_at_googlemail.com>
Date: Wed, 09 Mar 2011 15:02:31 +1300


Dear list,

Reading the help page for ?switch didn't give me more than a hint at what's going on here,

x = 5
y = 2

foo <- function(a="x"){

     switch(a, "x" = x,
                     "y" = y)

}

foo(factor('x', levels=c('y', 'x')))

# 2

It seems that switch, when given a factor, uses the numeric codes rather than the string levels as I would have naively expected. Is this deliberate, should it be mentioned on the help page? I had an input that had been invisibly converted to a factor by data.frame(); using switch resulted in serious confusion.

Thanks,

baptiste



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