Maybe I am misunderstanding you, but I think it is documented? The help
page says
switch(EXPR, ...)
[...]
If the value of ‘EXPR’ is not a character string it is coerced to
integer. [...]
Since
is.character( factor('x', levels=c('y', 'x')) )
[1] FALSE
you get
as.integer( factor('x', levels=c('y', 'x')) )
[1] 2
from the "coerced to integer" part? Therefore the second statement (y)
is evaluated regardless of the label ("y"=).
Allan
On 09/03/11 02:02, baptiste auguie wrote:
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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