removeConstantFeatures: Remove constant features from a data set.
Description
Constant features can lead to errors in some models and obviously provide
no information in the training set that can be learned from.
With the argument perc, there is a possibility to also remove
features for which less than perc percent of the observations
differ from the mode value.
Usage
removeConstantFeatures(x, target, perc = 0, dont.rm = character(0L),
na.ignore = FALSE, tol = .Machine$double.eps^0.5,
show.info = getMlrOption("show.info"))