Initialise a complete empty data frame (no rows, no columns) [duplicate]

Question

Here's a hack to create an empty data frame with no rows and no columns:

iris[FALSE, FALSE]
#> data frame with 0 columns and 0 rows

Smarter-looking code creates a spurious column:

x <- list(NULL)
class(x) <- c("data.frame")
attr(x, "row.names") <- integer(0)
str(x)
#> 'data.frame':    0 obs. of  1 variable:
#>  $ : NULL

Is there a non-hack alternative?

The reason to create such a thing is to satisfy a function that can handle empty data frames but not NULLs.

This is different from similar questions because it is about having no columns as well as no rows.

Answer 1

df <- data.frame()
str(df)
'data.frame':   0 obs. of  0 variables

Answer 2

empty.data.frame <- function() {
  structure(NULL,
            names = character(0),
            row.names = integer(0),
            class = "data.frame")
}
empty.data.frame()
#> data frame with 0 columns and 0 rows

# thelatemail's suggestion in a comment (fastest)
empty.data.frame2 <- function() {
  structure(NULL, class="data.frame")
}

library(microbenchmark)
microbenchmark(data.frame(), empty.data.frame(), empty.data.frame2())
#> Unit: microseconds
#>                 expr    min      lq     mean median     uq    max neval
#>         data.frame() 12.831 13.4485 15.18162 13.879 14.378 65.967   100
#>   empty.data.frame()  8.323  9.0515  9.76106  9.363  9.732 19.427   100
#>  empty.data.frame2()  5.884  6.9650  7.63442  7.240  7.540 17.746   100