How to skip column when reading CSV file?

Question

In accordance with the documentation of read.csv, colClasses argument:

Possible values are ..., "NULL" (when the column is skipped), ...

But looks like it doesn't work when col.names is used:

columnHeaders <- c("column1", "column2", "column_to_skip")
columnClasses <- c("factor", "factor", NULL)
data <- read.csv(fileCSV, header = FALSE, sep = ",", col.names = columnHeaders, colClasses = columnClasses)

In result data contains 3 columns, including column_to_skip. What is the proper way to read csv without this last column?

After you do this, check out how much easier it is with data.table::fread() — Rich Scriven
– Rich Scriven, Commented Mar 29, 2015 at 18:03

lukeA · Accepted Answer · 2015-03-29 17:59:03Z

9

use "NULL" instead of NULL:

csv <- "1,2,3
4,5,6"
read.csv(text = csv, header = FALSE, colClasses = c("integer", "integer", "NULL"))
#   V1 V2
# 1  1  2
# 2  4  5

answered Mar 29, 2015 at 17:59

lukeA

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