It seems that I found micro bug in Python documentation describing collections.Counter class.

There is the following snippet of code

c.most_common()[:-n:-1]         # n least common elements

Actually this expression returns not n least common elements, but rather n - 1, beacuse second boundary  is not included (as usual with slices).

You probably meant c.most_common()[-n:] or c.most_common()[:-n-1:-1] if reverse ordering is nesessary.

 

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Best regards
Mikhail Golubev