This is an interal function for use by "bootstrap_diff" only.
get_diff(xy, xn)The data for the genes which are annotated to the cell-cycle, i.e.
those genes for which "if_cc" is TRUE.
The data for the genes which are not annotated to the cell-cycle,
control genes, genes for which "if_cc" is FALSE
A data frame containing the loadings for each component on the cell-cycle and control genes.