Get the maximum value of a column for each unique value in another column, grouped on another column

Question

I want to get the maximum value for a column for each unique value in another column and grouped by another column.

Say I have the following:

Ticker,Bid,Year
ROG SW,8.0,19
ROG SW,9.0,20
ROG SW,9.5,20
NOVN SW,2.0,19
NESN SW,3.0,19
DAI GR,2.5,20
DAI GR,3.0,19
DAI GR,4.0,19

I would like this to then be:

Ticker,Bid,Year
ROG SW,8.0,19
ROG SW,9.5,20
NOVN SW,2.0,19
NESN SW,3.0,19
DAI GR,2.5,20
DAI GR,4.0,19

So the maximum bid for each year for each ticker.

I know I can use:

 df.groupby(['Ticker'], sort=False)['Bid'].max() 

but I need to do this for each unique year. Thanks

Answer 1

Try:

df.groupby(['Ticker','Year'], as_index=False).max()

Output:

    Ticker  Year  Bid
0   DAI GR    19  4.0
1   DAI GR    20  2.5
2  NESN SW    19  3.0
3  NOVN SW    19  2.0
4   ROG SW    19  8.0
5   ROG SW    20  9.5