scikit-learn/scikit-learn — pull request #1066 by amueller (2012-08-26 12:44:08+00:00)
Title: MRG added min_df keyword to CountVectorizer, default=2

This is a resurrection of #348.
As this was before @ogrisel's rewrite, I just wrote it from scratch.
I used the float/int convention that is now widely used throughout the scikit (for example in cv).

I took the liberty of making the default for ``min_df`` two, as I feel that is still very conservative and should always improve performance. I corrected all the doctests for that.
This does change results compared to previous versions and if someone is -1, I can set the default back to one.