Calculating the number of specific consecutive equal values in a vectorized way in pandas

Question

Let\'s say we have the following pandas DataFrame:

In [1]:
import pandas as pd
import numpy as np

df = pd.DataFrame([0, 1, 0, 0, 1, 1, 0, 1, 1, 1], columns=         


        

Answer 1

You can do something like this(credit goes to: how to emulate itertools.groupby with a series/dataframe?):

>>> df['in'].groupby((df['in'] != df['in'].shift()).cumsum()).cumsum()
0    0
1    1
2    0
3    0
4    1
5    2
6    0
7    1
8    2
9    3
dtype: int64