haven now supports selective column and row reading

[leeper]

Please specify whether your issue is about:

• a possible bug
• a question about package functionality
• a suggested code or documentation change, improvement to the code, or feature request

[mikmart]

One consequence of the haven changes that was just brought up in this Stack Overflow question is that col_select in haven's reader functions is a quoted argument and shouldn’t be evaluated early:

f <- tempfile(fileext = ".sas7bdat")
haven::write_sas(mtcars, f)

haven::read_sas(f, col_select = mpg)
#> # A tibble: 32 x 1
#>      mpg
#>    <dbl>
#>  1  21  
#>  2  21  
#>  3  22.8
#>  4  21.4
#>  5  18.7
#>  6  18.1
#>  7  14.3
#>  8  24.4
#>  9  22.8
#> 10  19.2
#> # ... with 22 more rows
rio::import(f, col_select = mpg)
#> Error in rio::import(f, col_select = mpg): object 'mpg' not found

[leeper]

Thanks. That's useful to know.

[bokov]

col_select in haven's reader functions is a quoted argument and shouldn’t be evaluated early

Actually, both the haven functions and the dplyr::select() method to which their documentation refers permit quoted column names.

[mikmart]

@bokov yeah, what I meant was that when bare column names are passed, col_select needs to be evaluated in the appropriate context to avoid the "object not found" errors.

At the moment all ... args to import() are put in a list: https://github.com/leeper/rio/blob/ba74db92ecdb6d47b80c172359b58f60d388ba11/R/import.R#L129
That then forces evaluation on all of them.

[bokov]

We could just advise users to enclose the col_select argument in quotes or wrap it in quote() in the help file... would that address the problem?