sk-learn - ValueError: array is too big.
The problem is that you're converting a large sparse dataset into a dense array via toarray(). Don't do that :) Why do you need it in dense array format? Try posting more of your code to see if we can figure out better ways to solve the problem. With any large dataset, you want to stay sparse as long as possible and only work with smaller sets of dense data (if dense is needed at all).