For col_types, using a named vector should error

[ginolhac]

Dear Jenny,

I am using readr CRAN version 2.1.2 and playing around with col_types(). If we specify the columns and their types in the dedicated cols() function it works. The document of cols() says:

In general you can substitute list() for cols() without changing the behavior.

It works for using list() but using c() issued no warnings and the wrong output. The col_type specified is ignored.

I suggest col_types() should only accept cols() and cols_only() as arguments for robustness.

Best wishes

see reprex below:

library(readr)
# be default will be read as character
read_csv("A\n1\na", show_col_types = FALSE)
#> # A tibble: 2 × 1
#>   A    
#>   <chr>
#> 1 1    
#> 2 a

# forcing it to be double, got expected NA
read_csv("A\n1\na", show_col_types = FALSE,
         col_types = cols(A = col_double()))
#> Warning: One or more parsing issues, see `problems()` for details
#> # A tibble: 2 × 1
#>       A
#>   <dbl>
#> 1     1
#> 2    NA

# cols() doc https://readr.tidyverse.org/reference/cols.html
# says that we can 'In general substitute list() for cols()'
# works as expected
read_csv("A\n1\na", show_col_types = FALSE,
         col_types = list(A = col_double()))
#> Warning: One or more parsing issues, see `problems()` for details
#> # A tibble: 2 × 1
#>       A
#>   <dbl>
#> 1     1
#> 2    NA

# substitute list() for c() and we got no warning
# and the wrong column type back: a character
read_csv("A\n1\na", show_col_types = FALSE,
         col_types = c(A = col_double()))
#> # A tibble: 2 × 1
#>   A    
#>   <chr>
#> 1 1    
#> 2 a

^{Created on 2022-03-24 by the reprex package (v2.0.1)}

Session info

sessioninfo::session_info()
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