Several other data transformations are available and applicable to different situations. A summary of these transformations can be found at the documentation site for the caret package under Pre-Processing at https://topepo.github.io/caret/pre-processing.html.

The options available in the pre-process function of caret can be found from its help section, by running the command ?preProcess in RStudio. The code for it is given here:

Method 
 
a character vector specifying the type of processing. 
 
Possible values are "BoxCox", "YeoJohnson", "expoTrans", "center", "scale", "range", "knnImpute", "bagImpute", "medianImpute", "pca", "ica", "spatialSign", "corr", "zv", "nzv", and "conditionalX" (see Details below)