I would like to create a new column target based on the values on the source column. I simply want to assign values from this list [6,7,8,9,10,11,12,13] to the rows of the source column
value source
0 0.83 0
1 0.99 0
2 0.20 0
3 0.79 0
4 0.19 0
5 0.86 0
6 0.31 1
7 0.19 1
8 0.50 2
9 0.44 2
10 1.00 2
11 0.67 2
12 0.74 3
13 0.43 3
14 0.21 3
15 0.03 4
16 1.00 4
17 0.57 4
18 0.67 5
19 1.00 5
expected output
value source target
0 0.83 0 6
1 0.99 0 7
2 0.20 0 8
3 0.79 0 9
4 0.19 0 10
5 0.86 0 11
6 0.31 1 6
7 0.19 1 7
8 0.50 2 6
9 0.44 2 7
10 1.00 2 8
11 0.67 2 9
12 0.74 3 6
13 0.43 3 7
14 0.21 3 8
15 0.03 4 6
16 1.00 4 7
17 0.57 4 8
18 0.67 5 6
19 1.00 5 7
CodePudding user response：
Use GroupBy.cumcount with mapping by dictioanry created from list with enumerate:
L = [6,7,8,9,10,11,12,13]
df['target'] = df.groupby('source').cumcount().map(dict(enumerate(L)))
print (df)
value source target
0 0.83 0 6
1 0.99 0 7
2 0.20 0 8
3 0.79 0 9
4 0.19 0 10
5 0.86 0 11
6 0.31 1 6
7 0.19 1 7
8 0.50 2 6
9 0.44 2 7
10 1.00 2 8
11 0.67 2 9
12 0.74 3 6
13 0.43 3 7
14 0.21 3 8
15 0.03 4 6
16 1.00 4 7
17 0.57 4 8
18 0.67 5 6
19 1.00 5 7