extract_vector_from_compressed_matrix: Extract vector from compressed matrix
In Timothy-Barry/ravel:

A function to extract a vector(s) from a matrix stored in compressed column or row format

extract_vector_from_compressed_matrix(
  vector_nos,
  x,
  i,
  p,
  vector_length,
  zero_based_idx = TRUE,
  vector_subset = NULL
)

`vector_nos`	indexes of the vectors to extract
`x`	sparse-matrix data
`i`	sparse-matrix indexes
`p`	sparse-matrix pointers
`vector_length`	length of the vectors to extract
`zero_based_idx`	(boolean; default TRUE) do i and p use zero-based indexing?
`vector_subset`	(optional) integers indicating a subset of the vectors to return