Improve aggregate.default ...?

aggregate(dat["A"], dat["Group"], mean)

Hi,

I find it a bit annoying that aggregate.default forces the returned
object to loose the 'name' of the variable aggregated, replacing it with
'x'.

A brief example:

dat <- data.frame(A = runif(100), B = rnorm(100),

+ ? ? ? ? ? ? ? ? ? Group = gl(4, 25))

with(dat, aggregate(A, by = list(Group = Group), FUN = mean))

?Group ? ? ? ? x
1 ? ? 1 0.6523228
2 ? ? 2 0.4544317
3 ? ? 3 0.4619624
4 ? ? 4 0.4703156

This arises because aggregate default has:

function (x, ...)
{
? ?if (is.ts(x))
? ? ? ?aggregate.ts(as.ts(x), ...)
? ?else aggregate.data.frame(as.data.frame(x), ...)
}

which recasts x as a data frame, but doesn't make any effort to supply a
name. Can we do a better job of supplying a useful name?

My first attempt is:

aggregate.default <- function(x, ...) {
? ?if (is.ts(x))
? ? ? ?aggregate.ts(as.ts(x), ...)
? ?else {
? ? ? ?nam <- deparse(substitute(x))
? ? ? ?x <- as.data.frame(x)
? ? ? ?names(x) <- nam
? ? ? ?aggregate.data.frame(x, ...)
? ?}
}

Which works for the brief example above:

with(dat, aggregate(A, by = list(Group = Group), FUN = mean))

?Group ? ? ? ? A
1 ? ? 1 0.4269715
2 ? ? 2 0.5479352
3 ? ? 3 0.5091543
4 ? ? 4 0.4926412

However, it fails make check-all because examples have relied on
returned object having 'x'. I also note that this might have the
annoying side effect of producing odd names if we use the following
incantation:

res <- aggregate(dat$A, by = list(Group = dat$Group), FUN = mean)
str(res)

'data.frame': ? 4 obs. of ?2 variables:
?$ Group: Factor w/ 4 levels "1","2","3","4": 1 2 3 4
?$ dat$A: num ?0.427 0.548 0.509 0.493

res$dat$A

Error in res$dat$A : $ operator is invalid for atomic vectors

res$`dat$A`

[1] 0.4269715 0.5479352 0.5091543 0.4926412

Is there a way of coming up with a better way to name the aggregated
variable? Would a change of this kind be something R Core would consider
making to aggregate.default if a good solution is found?

Thanks in advance,

G
--
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