How to count the number of times a condition consecutively exists across rows in a column in pandas

I have a simple df like this:

    data
0    0
1    0
2    1
3    1
4    0
5    0
6    1
7    1
8    1
9    1

I am interested in counting the number of times 1 consecutively occurs, and then creating a column assigning that value to each row in the chunk. It should look like this:

    data   count
0    0       0
1    0       0
2    1       2
3    1       2
4    0       0
5    0       0
6    1       4
7    1       4
8    1       4
9    1       4

Is there a simple pandas way to do this?

>Solution :

Use np.where, cumsum

s=df.groupby((df['data']!=df['data'].shift(1)).cumsum()).transform('count')
df['count']=np.where(df['data'].eq(1),s['data'],0)



    data  count
0     0      0
1     0      0
2     1      2
3     1      2
4     0      0
5     0      0
6     1      4
7     1      4
8     1      4
9     1      4