通过另一列 pandas 找到列组的最大值

Question

I have a dataframe with 2 columns:

count percent  grpno.
0          14.78       1
1           0.00       2
2           8.80       3
3           9.60       4
4          55.90       4
5           0.00       2
6           0.00       6
7           0.00       5
8           6.90       1
9          59.00       4

I need to get the max of column 'count percent ' and group by column 'grpno.'. Though I tried doing the same by

geostat.groupby(['grpno.'], sort=False)['count percent'].max()

I get the output to be

grpno.
1    14.78
2     0.00
3     8.80
4    59.00
6     0.00
5     0.00
Name: count percent, dtype: float64

But I need output to be a dataframe that has the column name modified as 'MaxOfcount percent' and 'grpno.' Can anyone help on this? Thanks

Answer 1

res = df.groupby('grpno.')['count percent'].max().reset_index()
res.columns = ['grpno.', 'MaxOfcount percent']

   grpno.  MaxOfcount percent
0       1               14.78
1       2                0.00
2       3                8.80
3       4               59.00
4       5                0.00
5       6                0.00

You could also do it in one line:

res = df.groupby('grpno.', as_index=False)['count percent'].max().rename(columns={'count percent': 'MaxOfcount percent'})

Answer 2

You could use groupby with argument as_index=False :

In [119]: df.groupby(['grpno.'], as_index=False)[['count percent']].max()
Out[119]: 
   grpno.  count percent
0       1    14.78
1       2     0.00
2       3     8.80
3       4    59.00
4       5     0.00
5       6     0.00

df1 = df.groupby(['grpno.'], as_index=False)[['count percent']].max()
df1.columns = df1.columns[:-1].tolist() + ['MaxOfcount percent']

In [130]: df1
Out[130]: 
   grpno.  MaxOfcount percent
0       1               14.78
1       2                0.00
2       3                8.80
3       4               59.00
4       5                0.00
5       6                0.00