target
[character(1) | character(2) | character(n.classes)]
Name(s) of the target variable(s).
Only used when obj is a data.frame, otherwise ignored.
If survival analysis is applicable, these are the names of the survival time and event columns,
so it has length 2.
For multilabel classification these are the names of logical columns that indicate whether
a class label is present and the number of target variables corresponds to the number of
classes.
on.constant
[character(1)]
How should constant vectors be treated? Only used, of “method != center”,
since this methods does not fail for constant vectors. Possible actions are:
“quiet”: Depending on the method, treat them quietly:
“scale”: No division by standard deviation is done, input values.
will be returned untouched.
“standardize”: Only the mean is subtracted, no division is done.
“range”: All values are mapped to the mean of the given range.
“warn”: Same behaviour as “quiet”, but print a warning message.
“stop”: Stop with an error.