dplyr：根据data_frame每行中的值下载文件

Question

I am trying to download a file based on the values in the rows of a data_frame . Here is what the data_frame looks like:

df_foo = data_frame(
  input_id = 1:10, 
  file_name_id = 20:30
) 

Here is an attempt using by_row from the purrr package which does not work.

df_foo %>% 
  by_row(
    .f = download.file, 
    url = paste0("http://foobar.com/id=", input_id),
    destfile = paste0("file number", file_name_id, ".txt")
  )

I have also tried invoke_rows ( map_rows ). Any solution that would work in pipes would be appreciated.

Answer 1

With rowwise :

df_foo %>%
     rowwise %>%
     do(f=download.file(paste0("http://example.com/id=", .$input_id),
                        paste0("file_", .$filename_id)))

But do you really need dplyr?

mapply(download.file, paste0("http://example.com/id=", df_foo$input_id),
                      paste0("file_", df_foo$filename_id))