Numbering Sequences in pandas-CodePudding

I have the following dataframe:

   Steps
0  False
1  False
2  True
3  True
4  True
5  False
6  True
7  True
8  False
9  False 
10 False
11 True

I would like to number the True sequences in an additional column:

   Steps  Numbered
0  False  0
1  False  0
2  True   1
3  True   1
4  True   1  
5  False  0
6  True   2
7  True   2
8  False  0
9  False  0
10 False  0
11 True   3

Filling the rows containing False is secondary. Do you have any ideas?

CodePudding user response：

You can use the values that are both True and different from the previous one (using diff) to initiate a cumsum:

df['Numbered'] = (df['Steps']&df['Steps'].diff()).cumsum().where(df['Steps'], 0)

output:

    Steps  Numbered
0   False         0
1   False         0
2    True         1
3    True         1
4    True         1
5   False         0
6    True         2
7    True         2
8   False         0
9   False         0
10  False         0
11   True         3

CodePudding user response：

Chain shifted values by Series.shift by & for bitwise AND for counter by first Trues and then set False rows to 0 by Series.where:

df['Numbered'] = ((df['Steps'] & ~df['Steps'].shift(fill_value=False)).cumsum()
                       .where(df['Steps'], 0))
print (df)
    Steps  Numbered
0   False         0
1   False         0
2    True         1
3    True         1
4    True         1
5   False         0
6    True         2
7    True         2
8   False         0
9   False         0
10  False         0
11   True         3

Solution working well if first value is True:

df['Numbered'] = ((df['Steps'] & ~df['Steps'].shift(fill_value=False)).cumsum()
                       .where(df['Steps'], 0))
print (df)
    Steps  Numbered
0    True         1
1   False         0
2    True         2
3    True         2
4    True         2
5   False         0
6    True         3
7    True         3
8   False         0
9   False         0
10  False         0
11   True         4