Readr read_csv - select column by index

[AJF]

Hi,

I was wondering whether there is a way to use readr::read_csv() to read a csv file, but only read select columns - by index. For example, can I read in the first 3 columns , or the 2nd, 5th, and 9th columns (where I do not necessarily know the column names in advance)?

Thank you!

[woodward]

I think you can do it with data.table::fread

[siddharthprabhu]

You can do it by passing a string of the standard type abbreviations to the col_types() parameter.

Use _ or - to skip columns you don't want. You can manually specify the type of each column that you want to read or use ? to allow the parser to guess.

Here's an example:

readr::read_csv("1,2,3,4\n5,6,7,8", col_names = FALSE, col_types = "?_?_")
#> # A tibble: 2 x 2
#>      X1    X3
#>   <dbl> <dbl>
#> 1     1     3
#> 2     5     7

^{Created on 2020-06-30 by the reprex package (v0.3.0)}