I need to transform a large array into a set of indicies that relate
back to actual values within each
column of the array.

For instance - suppose there was a list of 10,000 values in a column,
but there were only 20 unique values in that 10,000. I could transform
the 10,000 into the 20 if I had a way of finding them. (Or at least
that's the direction I'm headed).

This would require 1) Finding an array of unique values, 2) creating a
second array with similar dimensions (n x m) as an original array that
for each value of m goes through something like the
following:


Original array: n1 x m1 array
Unique values of n1 for each value of m1 in m1 arrays
Transformed array: n2 x m1 where n1 has been replaced by the index of
each unique n1 value within the column m1

All where n1 and m1 represent the size of the array