python - Incrementing contiguous positive groups in array/Series -

suppose have pandas series of boolean values so.

vals = pd.series([0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1]).astype(bool)  >>> vals 0     false 1     false 2     false 3      true 4      true 5      true 6      true 7     false 8     false 9      true 10     true 11    false 12     true 13     true 14     true dtype: bool 

i want turn boolean series series each group of 1's enumerated,

0     0 1     0 2     0 3     1 4     1 5     1 6     1 7     0 8     0 9     2 10    2 11    0 12    3 13    3 14    3 

how can efficiently?

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i have been able manually, looping on series on python level , incrementing, slow. i'm looking vectorized solution - saw this answer unutbu concerning splitting on increasing groups in numpy, , trying work cumsum of sort have been unsuccessful far.

you can try this:

vals.astype(int).diff().fillna(vals.iloc[0]).eq(1).cumsum().where(vals, 0)  #0     0 #1     0 #2     0 #3     1 #4     1 #5     1 #6     1 #7     0 #8     0 #9     2 #10    2 #11    0 #12    3 #13    3 #14    3 #dtype: int64