I'm very new to pandas so I hope this will have an easy answer (and I also appreciate all pointers to even the setup of the dataframe)
So let's say I have the following DataFrame:
D = pd.DataFrame({ i:{ "name":str(i),
"vector": np.arange(i,i+10),
"sq":i**2,
"gp":i%3 } for i in range(10) }).T
gp name sq vector
0 0 0 0 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
1 1 1 1 [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
2 2 2 4 [2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
3 0 3 9 [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
4 1 4 16 [4, 5, 6, 7, 8, 9, 10, 11, 12, 13]
5 2 5 25 [5, 6, 7, 8, 9, 10, 11, 12, 13, 14]
6 0 6 36 [6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
7 1 7 49 [7, 8, 9, 10, 11, 12, 13, 14, 15, 16]
8 2 8 64 [8, 9, 10, 11, 12, 13, 14, 15, 16, 17]
9 0 9 81 [9, 10, 11, 12, 13, 14, 15, 16, 17, 18]
Now I would like to group by "gp" and get the mean of the "vector"
I've tried
D.groupby('gp').mean()
and even
D.groupby('gp').agg( np.mean )
but I get an error that there were no "numeric types" to be aggregated. So do np.arrays not work in pandas?
See Question&Answers more detail:
os