Hello R useRs,
I have a function which returns a list of functions :
freq1 <- function(x) {
lev <- unique(x[!is.na(x)])
nlev <- length(lev)
args <- alist(x=)
if (nlev == 1) {
body <- c("{", "sum(!is.na(x))", "}")
f <- function() {}
formals(f) <- as.pairlist(args)
body(f) <- parse(text = body)
namef <- paste("freq", as.character(nlev), sep = "_")
assign(namef, f)
res <- list(get(namef))
names(res) <- namef
}
if (nlev > 1) {
res <- NULL
namesf <- NULL
for (i in 1:nlev) {
body <- c("{", paste("sum(x[!is.na(x)] ==", as.character(lev[i]), ")",
sep = " "), "}")
f <- function() {}
formals(f) <- as.pairlist(args)
body(f) <- parse(text = body)
namef <- paste("freq", as.character(lev[i]), sep = "_")
assign(namef, f)
namesf <- c(namesf, namef)
res <- c(res, get(namef))
}
names(res) <- namesf
}
return(res)
}
df <- data.frame(id = 1:50, x = sample(c(NA, 1), 50, T), y = sample(1:2, 50,
T), z = sample(letters[1:2], 50, T))
> freq1(df$x)
$freq_1
function (x)
{
sum(!is.na(x))
}
<environment: 0x03d99684>
> freq1(df$y)
$freq_2
function (x)
{
sum(x[!is.na(x)] == 2)
}
<environment: 0x03d6c930>
$freq_1
function (x)
{
sum(x[!is.na(x)] == 1)
}
<environment: 0x03d6c930>
I would like to use this list of functions with cast function (in package
reshape by Hadley Wickham) :
> cast(melt(df, id = c("id", "z"), measure = c("x", "y")), variable +
result_variable ~ z, fun = function(x) freq1(x), margins = "grand_col")
Erreur dans freq1(x) : objet "res" non trouvé
Here the result I would like to have :
variable a b (all)
1 x freq_1 10 14 24
2 y freq_1 18 32 50
3 y freq_2 9 14 23
I admit it is a bit far-fetched, but is this actually possible ?
Thank you very much.
David
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