Pandas: Compute The Mean Of A Column Grouped By Another Column

Say I have a dataframe like this: gender height weight C 2000-01-01 male 42.849980 157.500553 1 2000-01-02 male 49.607315 177.340407 1 2000-01-03

Solution 1:

Your syntax is incorrect, there is no groupby arg for mean, you want to groupby on the col of interest and then call mean on the column of interest:

In [11]:
df.groupby('C')['height'].mean()

Out[11]:
C
1    54.299919
2    52.760444
3    67.672566
Name: height, dtype: float64