Python create an empty sparse matrix

Question

I am trying to parse some real data into a .mat object to be loaded in my matlab script.

I am getting this error:

TypeError: \'co

Answer 1

Use a sparse format, which supports efficient indexing, like dok_matrix

This is an efficient structure for constructing sparse matrices incrementally.

...

Allows for efficient O(1) access of individual elements. Duplicates are not allowed. Can be efficiently converted to a coo_matrix once constructed.

The last sentence can be generalized to: can be efficiently converted to all the other common formats if needed.

from scipy.sparse import dok_matrix

M = dok_matrix((100, 100))  # extra brackets needed as mentioned in comments
                            # thanks Daniel!
M[0,3] = 5