Create CV Folds

createfolds splits the data into k groups. Taken from the caret package (see references for details)

createfolds(y, k = 10, list = FALSE, returnTrain = FALSE)

Arguments

y	vector of response
k	integer for the number of folds.
list	logical - should the results be in a list (TRUE) or a matrix
returnTrain	a logical. When true, the values returned are the sample positions corresponding to the data used during training. This argument only works in conjunction with `list = TRUE`

A vector of CV fold ID's for each observation in y

For numeric y, the sample is split into groups sections based on percentiles and sampling is done within these subgroups