Feature: Avoid warning when having additional colClasses in `fread`
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Assessment
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Newbie friendliness
- 35/100
Research direction
Start by reproducing the supplied fread example with the extra d entry in colClasses, then trace the fread handling of column names and warnings. Done means there is a documented way to avoid the warning for absent columns while preserving the requested types for columns that are present.
Written by the indexing model from the issue text.
Description
In some cases I have csv file where I know the columns that can exist and their types. However not always all types are present. Currently if you specify columns that are not present a warning is raised (see example below). It seems there is not option to avoid this warning? It would be great to have an option to switch it off. For files a work around might be to first read the header and then subset colClasses but that option is more tricky for commands as an input.
require(data.table)
#> Loading required package: data.table
fread('a,b
1,"a"
2,"b"', header=T, sep=',',
colClasses=c('a'='numeric',b='character',d='integer'))
#> Warning in fread("a,b\n 1,\"a\"\n 2,\"b\"", header = T, sep = ",", : Column name
#> 'd' (colClasses[[2]][1]) not found
#> a b
#> 1: 1 a
#> 2: 2 b
Created on 2021-12-16 by the reprex package (v2.0.1)
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