Given that I cannot arbitrarily change the data to make "a" an
integer, can I still use "a" as a grouping variable?
I tried melt(example, id = factor(a)) but it does not work either.
Must this change from numeric values to factors be done before
applying melt?
Thanks,
baptiste
On 25 Jul 2008, at 16:35, Dieter Menne wrote:
a <- as.numeric(1:10)
example <- list(data.frame(a=a, b=sin(a)), data.frame(a=a,
b=cos(a)))
melt(example, id = a) # this does not use a as an id variable
This is the documented behavior: Only integers and factors are used
for
grouping, but as.numeric is double, even if 1:10 looks like integers
a <- as.integer(1:10)
or simply
a <- 1:10
Dieter
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