Some sort of `lapply` function returning a named `list`

[mauriceR]

Is there a way to give the list which is return from lapply names within the function or is it only possible afterwards?

base function: lapply(1:2, function(x) x^2)

Wrapper function:

lapply2 <- function(X, FUN, names, ...) {
  xxx <- lapply(X, FUN, ...)
  names(xxx) <- names
  return(xxx)
}
lapply2(1:2, function(x) x^2, c("a", "b"))

This wrapper function works, but somehow I don't think this is the most elegant way.

[mauriceR]

I found an old example of lapply which was apparantly written in R and not in C.

la1 <- function(X, FUN, ...) {
    FUN <- match.fun(FUN)
    if (!is.list(X))
	X <- as.list(X)
    rval <- vector("list", length(X))
    for(i in seq(along = X))
	rval[i] <- list(FUN(X[[i]], ...))
    names(rval) <- names(X)		  # keep `names' !
    return(rval)
}

Thus, even if a package or function exists, you can't get better than following

lapply2 <- function (X, FUN, ...)  {
  names <- names(X)
  FUN <- match.fun(FUN)
  if (!is.vector(X) || is.object(X)) {
    X <- as.list(X)
  }
  names(X) <- names
  .Internal(lapply(X, FUN))
}

It would be nice though to know why the names were dropped in the first place.