But still the final output of the above example doesn't give the same output as mentioned. And i am not able to figure-out the issue.

Hi ! i find a small mistake or miss-out in the above code documented ?

def extract_features(docs):

return [doc2features(doc, i) for i in range(len(doc))]

instead "doc" needs to be replaced by docs or vice-versa. Please let me know if got it wrong.

Thanks