[Rcpp-devel] Performance question about DataFrame

Sure.  I'll write something up for the gallery, but here's the crude
outline.

Here's the C++ code:

Is C++ really necessary here?  I have the following R function in plyr:

quickdf <- function(list) {
  rows <- unique(unlist(lapply(list, NROW)))
  stopifnot(length(rows) == 1)

  names(list) <- make_names(list, "X")
  class(list) <- "data.frame"
  attr(list, "row.names") <- c(NA_integer_, -rows)

  list
}

which is basically equivalent (although I do some tricks with
rownames).  It's even more efficient if you copy and paste the
contents instead of calling the function because then that avoids
duplicating the input list, and instead modifies it in place.

Hadley

Chief Scientist, RStudio
http://had.co.nz/