extract_column_from_csc_matrix: Extract column from compressed sparse column matrix
In Timothy-Barry/ravel:

Extract column from compressed sparse column matrix

extract_column_from_csc_matrix(
  col_nos,
  csc_mat,
  zero_based_idx = TRUE,
  row_subset = NULL
)

`col_nos`	idxs of the columns to extract
`csc_mat`	a list representing a matrix stored in csc form containing the entries p, i, x, and dim.
`zero_based_idx`	(boolean) do i and p use zero-based indexing
`row_subset`	(optional) subset the extracted columns by row index