Increasing Rank based on year in pandas dataframe

Question

I have three dataframes for year 2022,year 2021 and year 2020 as given below:

ID  YEAR  RANK
500 2022   1
510 2022   2
520 2022   3

ID  YEAR  RANK
501 2021   1
550 2021   2
560 2021   3

ID  YEAR  RANK
505 2020   1
506 2020   2
507 2020   3

I have to append year 2020 dataframe below year 2021 dataframe and 2022 dataframe needs to be at top and reassign the rank as given in below output:

ID  YEAR  RANK
500 2022   1
510 2022   2
520 2022   3
501 2021   4
550 2021   5
560 2021   6
505 2020   7
506 2020   8
507 2020   9

In above output I need to reassign the rank in a way that rank for year 2022 dataframe needs to be same but for first Id of year 2021 rank needs to be 4 which 1 higher than highest rank for year 2022 and so on. Similarly for year 2020 if highest rank for year 2021 is 6 rank for first Id for year 2020 rank needs to be 7 and so on.

Asked By: Python_help

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Source

Answer 1

Add maximal rank to all ranks of df1 first and then use concat:

df2 = df2.assign(RANK = df2.RANK + df1.RANK.max())

df = pd.concat([df1, df2], ignore_index=True)
print (df)
    ID  YEAR  RANK
0  500  2022     1
1  510  2022     2
2  520  2022     3
3  501  2021     4
4  550  2021     5
5  560  2021     6

Answered By: jezrael

Increasing Rank based on year in pandas dataframe

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