If the col_names argument to fwf_positions() is a factor, then the return value of that function has a column named col_names that is also a factor, which causes read_fwf() to throw the error
Error: `col_names` must be TRUE, FALSE or a character vector
Reproducible example
# 1. Create a tibble with col_names as a factor
library(readr)
start_posns <- c(1, 2, 4, 8)
end_posns <- c(1, 3, 7, 15)
col_names <- factor(letters[1:4])
fwf_col_info <- fwf_positions(start_posns, end_posns, col_names)
glimpse(fwf_col_info)
## Observations: 4
## Variables: 3
## $ begin <dbl> 0, 1, 3, 7
## $ end <dbl> 1, 3, 7, 15
## $ col_names <fct> a, b, c, d
# 2. Write some data to file
tfile <- tempfile()
writeLines(
c("1AA1111aaaaaaaa", "2BB2222bbbbbbbb", "3CC3333cccccccc", "4DD4444dddddddd"),
tfile
)
# 3. Try to import it
read_fwf(tfile, fwf_col_info)
## Error: `col_names` must be TRUE, FALSE or a character vectorThoughts on fixes
Either fwf_positions() should convert factor col_names to character, or read_fwf() should allow factors and do the conversion itself, or both.
If the
col_namesargument tofwf_positions()is a factor, then the return value of that function has a column namedcol_namesthat is also a factor, which causesread_fwf()to throw the errorReproducible example
Thoughts on fixes
Either
fwf_positions()should convert factorcol_namesto character, orread_fwf()should allow factors and do the conversion itself, or both.