数据框按几列分组

Question

I have a dataframe like this

Quarter | Year | ID | Performance
Q1         2018   13   40
Q2         2019   37   60
.....

I would like to group the data not by a single column but I would like to have it grouped by year + quarter, so that I get sth like:

Q1 2019
ID | Performance

Q2 2019
ID | Performance

But when I use

df.groupby("Quarter").groupby("Year")

I get an error message that groupby cant be accessed for DataFrameGroupBy objects.

Answer 1

try like these

df.groupby(["Year", "Quarter"])

also call aggregate function as follows

df.groupby(['Year', 'Quarter']).agg({'ID' : 'first', 'Performance':'mean'})