which_are_constant {dataPreparation} R Documentation

Identify constant columns

Description

Find all the columns that are constant.

Usage

which_are_constant(data_set, keep_cols = NULL, verbose = TRUE)


Arguments

 data_set Matrix, data.frame or data.table keep_cols List of columns not to drop (list of character, default to NULL) verbose Should the algorithm talk (logical, default to TRUE)

Details

Algorithm is performing exponential search: it check constancy on row 1 to 10, if it's not constant it stops, if it's constant then on 11 to 100 ...
If you have a lot of columns than aren't constant, this function is way faster than a simple length(unique())! The larger the data_set set is, the more interesting it is to use this function.

Value

List of column's indexes that are constant in the data_set set.

Examples

# Let's load our data_set