Python Pandas：分组和平均？
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Python Pandas : group by in group by and average?
提问by UserYmY
I have a dataframe like this:
我有一个这样的数据框：
cluster org time
1 a 8
1 a 6
2 h 34
1 c 23
2 d 74
3 w 6
I would like to calculate the average of time per org per cluster.
我想计算每个集群每个组织的平均时间。
Expected result:
预期结果：
cluster mean(time)
1 15 ((8+6)/2+23)/2
2 54 (74+34)/2
3 6
I do not know how to do it in Pandas, can anybody help?
我不知道如何在 Pandas 中做到这一点，有人可以帮忙吗？
采纳答案by Zero
If you want to first take mean on the combination of ['cluster', 'org']and then take mean on clustergroups, you can use:
如果您想先对组合['cluster', 'org']取均值，然后对cluster组取均值，则可以使用：
In [59]: (df.groupby(['cluster', 'org'], as_index=False).mean()
.groupby('cluster')['time'].mean())
Out[59]:
cluster
1 15
2 54
3 6
Name: time, dtype: int64
If you want the mean of clustergroups only, then you can use:
如果您只想要cluster组的平均值，则可以使用：
In [58]: df.groupby(['cluster']).mean()
Out[58]:
time
cluster
1 12.333333
2 54.000000
3 6.000000
You can also use groupbyon ['cluster', 'org']and then use mean():
您还可以使用groupbyon['cluster', 'org']然后使用mean()：
In [57]: df.groupby(['cluster', 'org']).mean()
Out[57]:
time
cluster org
1 a 438886
c 23
2 d 9874
h 34
3 w 6
回答by Vince Payandeh
I would simply do this, which literally follows what your desired logic was:
我会简单地这样做，它实际上遵循您想要的逻辑：
df.groupby(['org']).mean().groupby(['cluster']).mean()
