Calculate ratio using groupby - pandas

Question

IM new using python
I created this dataframe:
d2= {'id': ['x2', 'x2', 'x2', 'x2', 'x3', 'x3', 'x3'], 'cod': [101001, 101001, 101001, 101001, 101002, 101002, 101002],
'flag': ['IN', 'IN', 'IN','CMP', 'IN', 'OUT', 'CMP'], 'col': [100, 100, 100, 300, 100, 300, 100]
}
df2 = pd.DataFrame(data=d2)
I want to calculate a ratio : (sum(IN)/sum(all) groupby id*cod.
The expected output should be
d2= {'id': ['x2', 'x2', 'x2', 'x2', 'x3', 'x3', 'x3'], 'cod': [101001, 101001, 101001, 101001, 101002, 101002, 101002],
'flag': ['IN', 'IN', 'IN','CMP', 'IN', 'OUT', 'CMP'], 'col': [0.5, 0.5, 0.5, 0.5, 0.2, 0.2, 0.2]
}
df2 = pd.DataFrame(data=d2)
Please tell me if im not clear. Thank you

Answer 1

First replace non matched values to 0 in DataFrame.where, aggregate sum and ast divide columns:
df3 = (df2.assign(new = df2['col'].where(df2['flag'].eq('IN'), 0))
.groupby(['id','cod'])
.transform('sum'))
df2['rat'] = df3['new'].div(df3['col'])
print (df2)
id cod flag col rat
0 x2 101001 IN 100 0.5
1 x2 101001 IN 100 0.5
2 x2 101001 IN 100 0.5
3 x2 101001 CMP 300 0.5
4 x3 101002 IN 100 0.2
5 x3 101002 OUT 300 0.2
6 x3 101002 CMP 100 0.2

Answer 2

You could create a temporary column (new), and use the temporary column, combined with groupby and transform, to get the ratio for each row::
(df2
.assign(
new = np.where(df2.flag == "IN", df2.col, 0),
ratio = lambda df : df.groupby(['id', 'cod'])
.pipe(lambda df: df['new']
.transform('sum')
.div(df['col'].transform('sum'))
)
)
)
id cod flag col new ratio
0 x2 101001 IN 100 100 0.5
1 x2 101001 IN 100 100 0.5
2 x2 101001 IN 100 100 0.5
3 x2 101001 CMP 300 0 0.5
4 x3 101002 IN 100 100 0.2
5 x3 101002 OUT 300 0 0.2
6 x3 101002 CMP 100 0 0.2

Answer 3

df2["col"] = df2.groupby(["id", "cod"], as_index=False)["col"].transform(
lambda x: x[df2.iloc[x.index]["flag"] == "IN"].sum() / x.sum(),
)
print(df2)
Prints:
id cod flag col
0 x2 101001 IN 0.5
1 x2 101001 IN 0.5
2 x2 101001 IN 0.5
3 x2 101001 CMP 0.5
4 x3 101002 IN 0.2
5 x3 101002 OUT 0.2
6 x3 101002 CMP 0.2