I know it sounds incorrect but that is the truth
Here let me show you
This below one is the first one and very widely used in the literature
First one reference : Steinbach, Michael, George Karypis, and Vipin Kumar. "A comparison of document clustering techniques." KDD workshop on text mining. Vol. 400. No. 1. 2000.
And the second one is this one : http://nlp.stanford.edu/IR-book/html/htmledition/evaluation-of-clustering-1.html
Here an answer about second one : https://stats.stackexchange.com/a/80194/5263
The second one is pretty complex and hard to understand
I coded both and they produce different results
I believe second one is better evaluation but the question is
Why there are 2 different F1-Measure? Which one is better and why?