scikit-learn/scikit-learn — pull request #3240 by JelleZijlstra (2014-06-04 02:38:45+00:00)
Title: fix defaultdict call

In Python 2.7, the current version fails with:

$ python -c 'from collections import defaultdict; defaultdict(None)'
Traceback (most recent call last):
File "", line 1, in
TypeError: first argument must be callable