Hey guys I have a data frame in python which looks something like the following

I want to add a column for year and repeat the rows with the number of years, something like

Does anyone have any advice on how I can go about doing this on Pandas? Thanks in advance!

CodePudding user response：

Try this:

l = [2020, 2021, 2022]
df.reindex(df.index.repeat(len(l))).assign(Year=np.tile(l, len(df)))

Output:

  FirstName MiddleName LastName  Year
0       Jim          J    Jones  2020
0       Jim          J    Jones  2021
0       Jim          J    Jones  2022
1   Anthony          K    White  2020
1   Anthony          K    White  2021
1   Anthony          K    White  2022
2      Ravi          K   Khanna  2020
2      Ravi          K   Khanna  2021
2      Ravi          K   Khanna  2022

Details, use reindex and repeat to expand dataframe to get the appropriate number of rows, then add a column 'Year' with assign and np.tile.

CodePudding user response：

You can do:

years = [2020,2021,2022]
df['Year'] = [years]*len(df)
df = df.explode('Year')

Output:

    FirstName   MiddleName  LastName    Year
0   Jim         J           Jones       2020
0   Jim         J           Jones       2021
0   Jim         J           Jones       2022
1   Anthony     K           White       2020
1   Anthony     K           White       2021
1   Anthony     K           White       2022
2   Ravi        K           Khanna      2020
2   Ravi        K           Khanna      2021
2   Ravi        K           Khanna      2022