Pandas combine df with a list by duplicating records for each list element-CodePudding

I have a df like this.

Date
2022-10-22
2022-10-21
2022-10-20

I want to combine and duplicate for each element in this list ['NAB', 'CBA']

To get a result df like this.

Date        Bank
2022-10-22  NAB
2022-10-22  CBA
2022-10-21  NAB
2022-10-21  CBA
2022-10-20  NAB
2022-10-20  CBA

Thanks in advance.

CodePudding user response：

Add fixed Bank=["NAB", "CBA"] column to df:

df["Bank"] = df.apply(lambda _: ["NAB", "CBA"], axis=1)

[Out]:
        date        Bank
0 2022-10-22  [NAB, CBA]
1 2022-10-21  [NAB, CBA]
2 2022-10-20  [NAB, CBA]

Then explode date column:

df = df.explode("Bank")

[Out]:
        date Bank
0 2022-10-22  NAB
0 2022-10-22  CBA
1 2022-10-21  NAB
1 2022-10-21  CBA
2 2022-10-20  NAB
2 2022-10-20  CBA

CodePudding user response：

You can use a cross merge:

lst = ['NAB', 'CBA']
out = df.merge(pd.Series(lst, name='Bank'), how='cross')

Output:

         Date Bank
0  2022-10-22  NAB
1  2022-10-22  CBA
2  2022-10-21  NAB
3  2022-10-21  CBA
4  2022-10-20  NAB
5  2022-10-20  CBA