scipy/scipy — pull request #3646 by perimosocordiae (2014-05-12 22:15:16+00:00)
Title: ENH: adding  `sum_duplicates` method to COO sparse matrix

Fixes https://github.com/scipy/scipy/issues/3624 by adding a `sum_duplicates` method and calling it before the `todok` conversion.

Also adds some test cases for both `sum_duplicates` and `todok` with duplicates.