scikit-learn/scikit-learn — comment on commit 64adbcaddd07f8d7777a290a387fbaf549600307
File: sklearn/utils/sparsefuncs.pyx line 11
By larsmans:

I don't think 32-bit integers are guaranteed by `scipy.sparse`; what they guarantee (more or less, the docs are very lacking), e.g. in the `sparsetools` module is that indices will be `int`. That might be 64 bits wide on some platforms (though I admit I can't think of an example).