Oh, this looks like it might be useful in the end:
Just as an aside, if your data is small enough to open up in excel, you might not need a sparse matrix at all.
You’re right. The way I’m hoping for this to work might only need to output something readable at the very last step, so converting to a dense array at that point probably doesn’t matter one way or another.
The data size is flexible though, eventually I would like to be able to use much larger sets than Excel could handle (wav files, basically)
Still a long way for me to go to get there though, 
, but I have the basic groundwork covered and can use Excel to evaluate outputs as I go in the meantime still to see if everything works as it should.