how to remove leading 0 record in each group pandas python

Question

suppose there are record

index	order	group	Data
1	1	A	0
2	2	A	0
3	3	A	0
4	4	A	1
5	5	A	2
6	6	A	1
7	1	B	0
8	2	B	2
9	3	B	-1
10	4	B	0
11	5	B	2
12	6	B	4

I would like to exclude leading 0 record Data in each group

Expecting result

index	order	group	Data
4	4	A	1
5	5	A	2
6	6	A	1
8	2	B	2
9	3	B	-1
10	4	B	0
11	5	B	2
12	6	B	4

how do I approached for this? I saw lstrip() but it only applied in each record.

Answer 1

Use GroupBy.cummax with comapre for not equal 0 in boolean indexing:

df1 = df[df['Data'].ne(0).groupby(df['group']).cummax()]
print (df1)
    index  order group  Data
3       4      4     A     1
4       5      5     A     2
5       6      6     A     1
7       8      2     B     2
8       9      3     B    -1
9      10      4     B     0
10     11      5     B     2
11     12      6     B     4