DavidDoukhan/nltk — comment on commit 70995823200d9c73798853afa0b42eeb84d020a8
File: nltk/metrics/ghd.py line 71
By jnothman:

In Python this is more idomatic as:

for i, ri in enumerate(rowv)

but because of the strange indexing, it would seem you then need to skip the first element.