How to create a pandas pivot table

Question

I have the following data frame and want to create a pivot table out of it.

Data Frame

ID  value
A   0.093392
A   0.130599
A   0.257946
A   0.274428
B   0.38097
B   0.321893
A   0.279304
D   0.305667
C   0.563479
F   0.216861
A   0.252754
A   0.259845
A   0.370912
E   0.190137
E   0.180974
E   0.178766
E   0.194251
G   0.208918
C   0.495991
D   0.449585
D   0.286733
D   0.425436
D   0.411018
B   0.374447
D   0.214219
A   0.357509
E   0.257467
E   0.058252
E   0.088913
D   0.17993

What I do is the following:

df.index = df['ID']
df_pvt = df.pivot_table(values='value',index='ID', columns=['value'], aggfunc='mean')

But I get

KeyError: 'value'

As far I understand, when I place columns as value and values as something else, it works, but I still do not get the desired data frame, as then instead of having one values column I get as many column as I have values.

Below is what the desired output should look like:

ID  Value
A   0.252965444
B   0.359103333
C   0.324656429
D   0.529735
E   0.216861
F   0.164108571
G   0.208918

Answer 1

It seems you don't need pivot_table here. You can use groupby to achieve desired result

df.groupby('ID')['Value'].mean()

Answer 2

Without groupby

df.set_index('ID').value.mean(level=0)
Out[26]: 
ID
A    0.252965
B    0.359103
D    0.324655
C    0.529735
F    0.216861
E    0.164109
G    0.208918
Name: value, dtype: float64