On 26 Jul 2008, at 02:52, hadley wickham wrote:
On Fri, Jul 25, 2008 at 8:50 PM, hadley wickham
<[EMAIL PROTECTED]> wrote:
On Fri, Jul 25, 2008 at 9:49 AM, baptiste auguie
<[EMAIL PROTECTED]> wrote:
Dear list,
I'm trying to use the reshape package to perform a merging
operation on a
list of data.frames as illustrated below,
a <- 1:10
example <- list( data.frame(a=a, b=sin(a)), data.frame(a=a,
b=cos(a)) )
melt(example, id = a)
You want:
melt(example, id = "a")
i.e. the id argument is a character or numeric vector specifying
which
variables to use as id variables. Your call would be equivalent to
melt(example, id = 1:10)
which clearly is incorrect for your example.
Sorry about the poor example, I hadn't realized it worked only thanks
to the default behavior.
I've just noticed that there's also a bug in the released version
(fixed in my development version) which means that the id argument to
melt.list() is not being passed on to the individual
melt.data.frame()s
Considering the following example, this makes sense:
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
melt(example[[1]], id = "a") # the method for the individual
data.frame works fine
Is it possible to install your development version of reshape? I could
not find it alongside of ggplot2 on github. If not, I've added "..."
in the method for the current version and it seems to work for me.
melt.list <- function(data, ..., level=1) {
var <- nulldefault(attr(data, "varname"), paste("L", level, sep=""))
names <- nulldefault(names(data), 1:length(data))
parts <- lapply(data, melt, level=level+1, ...)
namedparts <- mapply(function(x, name) {
x[[var]] <- name
x
}, parts, names, SIMPLIFY=FALSE)
do.call(rbind.fill, namedparts)
}
Many thanks,
baptiste
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