Look For Patterns In A Column Of Pandas Dataframe Based On The Value Of Other Column

I have the following dataframe : in each row where key==1, I would like to search s_w column for two occurrences of 1 before and after that row( where key==1) then sum value of v

Solution 1:

I think here is necessary add mask only by Series.where added to previous answer:

g = df[df['s_w'].eq(1)].groupby(['p','l'])['v']
df['c_s'] = g.shift(-1).add(g.shift(-2)).add(g.shift(2)).add(g.shift(1)).where(df['key'].eq(1))


print (df)
    p  l   w  s_w  key  v   c_s
0   1  1   1    1    1  2   NaN
1   1  1   2    1    1  2   NaN
2   1  1   3    0    0  5   NaN
3   1  1   4    0    0  3   NaN
4   1  1   5    0    0  4   NaN
5   1  1   6    1    1  5  10.0 <- 2 + 2 + 5 + 1
6   1  1   7    1    0  5   NaN
7   1  1   8    1    1  1  19.0 <- 5 + 5 + 5 + 4
8   1  1   9    0    0  2   NaN
9   1  1  10    0    0  3   NaN
10  1  1  11    0    0  4   NaN
11  1  1  12    1    0  5   NaN
12  1  1  12    1    1  4   NaN