Error in bind_rows_(x, .id) : Argument 1 must have names

Question

Here is a code snippet:

y <- purrr::map(1:2, ~ c(a=.x))
test1 <- dplyr::bind_rows(y)
test2 <- do.call(dplyr::bind_rows, y)

The fir

Answer 1

From the documentation of bind_rows:

Note that for historical reasons, lists containg vectors are always treated as data frames. Thus their vectors are treated as columns rather than rows, and their inner names are ignored

Here, your y as constructed has only inner names - it is two unnamed list elements, each containing a length-one vector with the vector element named a. So this error seems to be expected.

If you name the list elements, you can see that it behaves as described, with the vectors treated as columns:

library(tidyverse)
y <- map(1:2, ~ c(a=.x)) %>%
  set_names(c("a", "b"))
bind_rows(y)
#> # A tibble: 1 x 2
#>       a     b
#>   <int> <int>
#> 1     1     2

The difference with supplying y as arguments via do.call is that it's more like writing bind_rows(c(a = 1), c(a = 2)). This is not a list containing vectors, but separate vectors, so it binds by row as expected.