CODEWITHSUNDEEP
pythonpandas
Curious
Curious

Reputation: 113

Applying multiple functions (Mean., STD etc ) across columns in Python

I have this data of 4 columns and 8 rows...

df = pd.DataFrame([[1, 2, 3,7], [2, 8, 6,8],[3, 2, 3,7], [4, 4, 6,8],[5, 2, 3,7], [6, 1, 6,8],[7, 8, 3,7], [8, 9, 6,8]], columns=['time','A', 'B', 'C'])

       time  A  B  C
    0     1  2  3  7
    1     2  8  6  8
    2     3  2  3  7
    3     4  4  6  8
    4     5  2  3  7
    5     6  1  6  8  
    6     7  8  3  7
    7     8  9  6  8

I want to take mean and STD of column A and C, across columns not rows. e.g Mean and STD of 2 and 7 is "" (mean) and "3.535533906" (STD) respectively as following.

I want my result to look like this...

      Mean  STD
    0 4.7   3.535533906
    1 8     0
    2 .     .
    3 .     .
    . .     .
    . .     .

However, when I try to do

df= df.loc[(df.time>=2) & (df.time<=7),['A','C']],(['mean','std'])

I get the following error...

AttributeError: 'DataFrame' object has no attribute 'time'

I've tried to find solutions by doing this as well but in vain :

df= df.loc[(df.time>=2) & (df.time<=7),['A','C']].agg(['mean','std'])

but it gives me result of all rows mean and STD.

                 A         C
    mean  4.166667  7.500000
    std   3.125167  0.547723

How do I fix it?

Upvotes: 1

Views: 130

Answers (2)

BENY
BENY

Reputation: 323246

You can use describe

df[['A','C']].T.describe().T[['mean','std']]
Out[865]: 
   mean       std
0   4.5  3.535534
1   8.0  0.000000
2   4.5  3.535534
3   6.0  2.828427
4   4.5  3.535534
5   4.5  4.949747
6   7.5  0.707107
7   8.5  0.707107

Upvotes: 1

MaxU - stand with Ukraine
MaxU - stand with Ukraine

Reputation: 210842

Another way:

In [346]: df[['A','C']].T.agg(['mean','std']).T
Out[346]:
   mean       std
0   4.5  3.535534
1   8.0  0.000000
2   4.5  3.535534
3   6.0  2.828427
4   4.5  3.535534
5   4.5  4.949747
6   7.5  0.707107
7   8.5  0.707107

or as a new columns in the original DF:

In [347]: df[['Mean','STD']] = df[['A','C']].T.agg(['mean','std']).T

In [348]: df
Out[348]:
   time  A  B  C  Mean       STD
0     1  2  3  7   4.5  3.535534
1     2  8  6  8   8.0  0.000000
2     3  2  3  7   4.5  3.535534
3     4  4  6  8   6.0  2.828427
4     5  2  3  7   4.5  3.535534
5     6  1  6  8   4.5  4.949747
6     7  8  3  7   7.5  0.707107
7     8  9  6  8   8.5  0.707107

Upvotes: 4

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