Is a countvectorizer the same as tfidfvectorizer with use_idf=false?

Question

As the title states: Is a countvectorizer the same as tfidfvectorizer with use_idf=false ? If not why not ?

So does this also mean that adding

Answer 1

As larsmans said, TfidfVectorizer(use_idf=False, normalize=None, ...) is supposed to behave the same as CountVectorizer.

In the current version (0.14.1), there's a bug where TfidfVectorizer(binary=True, ...) silently leaves binary=False, which can throw you off during a grid search for the best parameters. (CountVectorizer, in contrast, sets the binary flag correctly.) This appears to be fixed in future (post-0.14.1) versions.