cartesianExpand         expands two data.frames using the Cartesian
                        product
makeDesign              make a uniform, random, or user-specified grid
                        over some columns of a data.frame, and combine
                        it with a grid of points to integrate over.
makePermutedDesign      creates a 'data.frame' with some columns
                        permuted
marginalPrediction      marginalizes prediction functions
permutationImportance   computes permutation importance
uniformGrid             method to create a uniform grid on a variable
