bit64 NA doesn't replicate in data.frame constructor

Question

While constructing a data-frame, columns are replicated if lengths differ.

> data.frame(x = c(1,2), y = NA_integer_)
  x  y
1 1 NA
2 2 NA

However, when I try to do this with bit64::NA_integer64_, I get an error. Does anyone know what could be happening? rep() works if it is called separately on bit64::NA_integer64_.

> data.frame(x = c(1,2), y = bit64::NA_integer64_)
Error in data.frame(x = c(1, 2), y = bit64::NA_integer64_) : 
  arguments imply differing number of rows: 2, 1
> rep(bit64::NA_integer64_, 2)
integer64
[1] <NA> <NA>

Answer 1

data.frame will only recycle:

• Vector with no attributes other than names
• factor
• AsIs character
• Date
• POSIXct

tibble doesn't have this problem.

tibble::tibble(x = c(1,2), y = bit64::NA_integer64_)
#> # A tibble: 2 x 2
#>       x       y
#>   <dbl> <int64>
#> 1     1      NA
#> 2     2      NA

Here is the relevant snippet from data.frame

for (i in seq_len(n)[nrows < nr]) {
    xi <- vlist[[i]]
    if (nrows[i] > 0L && (nr%%nrows[i] == 0L)) {
        xi <- unclass(xi)
        fixed <- TRUE
        for (j in seq_along(xi)) {
            xi1 <- xi[[j]]
            if (is.vector(xi1) || is.factor(xi1)) 
              xi[[j]] <- rep(xi1, length.out = nr)
            else if (is.character(xi1) && inherits(xi1, "AsIs")) 
              xi[[j]] <- structure(rep(xi1, length.out = nr), 
                class = class(xi1))
            else if (inherits(xi1, "Date") || inherits(xi1, "POSIXct")) 
              xi[[j]] <- rep(xi1, length.out = nr)
            else {
              fixed <- FALSE
              break
            }
        }
        if (fixed) {
            vlist[[i]] <- xi
            next
        }
    }
    stop(gettextf("arguments imply differing number of rows: %s", 
        paste(unique(nrows), collapse = ", ")), domain = NA)
}