Thank you Alberto !
This was also one of my points – to show that not always complicated algorithms are performing the best.
But still – did not expect to score best F1 !

Hello Giovanni !
Choice of parameters was mixture of experience, checking research papers and similar cases performance analysis and testing on the specific data set. I decided that lemmatisation and stemming are not good idea in this case as we will loose some context, while removing stopwords was a must. I am sorry not to try nltk stopword corpus – default sklearn corpus is known to have some issues.

There is a chance that neural network will do better job as extractor but given the time constraint I preferred to make s safe bet – using simple and fast methods. I intended to experiment with neural network as well, but … will do this these days and share the results as a followup to the article.