Python: Summarizing & Aggregating Groups and Sub-groups in DataFrame

问题

I am trying to build a table that has groups that are divided by subgroups with count and average for each subgroup. For example, I want to convert the following data frame:

To a table that looks like this where the interval is a bigger group and columns a thru i become subgroups within the group with the corresponding subgroups' count and average in each cell:

I have tried this with no success:

回答1:

Use DataFrame.melt with GroupBy.agg and tuples for aggregate functions with new columns names:

df1 = (df.melt('interval', var_name='source')
         .groupby(['interval','source'])['value']
         .agg([('cnt','count'), ('average','mean')])
         .reset_index())
print (df1.head())
  interval source  cnt  average
0        0      a    1      5.0
1        0      b    1      0.0
2        0      c    1      0.0
3        0      d    1      0.0
4        0      f    1      0.0

回答2:

Try.

df.groupby(['interval']).apply(lambda x : x.stack()
                                           .groupby(level=-1)
                                           .agg({'count', 'mean'}))

Use groupby with apply to apply a function for each group then stack and groupby again with agg to find count and mean.

回答3:

The following code solves the problem I asked for:

df.group(['interval'],,as_index=False).agg({
                                                'a':{"count":"mean"},
                                                'b':{"count":"mean"},
                                                'c':{"count":"mean"},
                                                'd':{"count":"mean"},
                                                'f':{"count":"mean"},
                                                'g':{"count":"mean"},
                                                'i':{"count":"mean"}
                                            })

来源：https://stackoverflow.com/questions/55663359/python-summarizing-aggregating-groups-and-sub-groups-in-dataframe