which_are_constant {dataPreparation} | R Documentation |
Find all the columns that are constant.
which_are_constant(data_set, keep_cols = NULL, verbose = TRUE)
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) |
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.
List of column's indexes that are constant in the data_set set.
# Let's load our data_set
data("messy_adult")
# Let's try our function
which_are_constant(messy_adult)
# Indeed it return constant the name of the constant column.