CODEWITHSUNDEEP
pythonpandasdataframe
Jacques Tebeka
Jacques Tebeka

Reputation: 321

Rename index of DataFrame in chain operation

I am trying to calculate the Jarque-Bera-Bera test (normality test) on my data that look like that (after chain operation) :

Data:

ranking Q1  Q2  Q3  Q4
Date                
2009-12-29  nan nan nan nan
2009-12-30  0.12    -0.21   -0.36   -0.39
2009-12-31  0.05    0.09    0.06    -0.02
2010-01-01  nan nan nan nan
2010-01-04  1.45    1.90    1.81    1.77
... ... ... ... ...
2020-10-13  -0.67   -0.59   -0.63   -0.61
2020-10-14  -0.05   -0.12   -0.05   -0.13
2020-10-15  -1.91   -1.62   -1.78   -1.91
2020-10-16  1.21    1.13    1.09    1.37
2020-10-19  -0.03   0.01    0.06    -0.02

I use a function like that :

(data
 .sort_values('Date')
 .groupby([pd.Grouper(key='Date', freq='B'), 'ranking'])
 ['perf_corr']
 .apply(lambda x: x.mean()*100)
 .unstack()
 .agg([lambda x: x.mean(),
       lambda x: np.sqrt(x.var()),
       lambda x: x.skew(),
       lambda x: x.kurtosis(),
  ])
)

The output is :

    Q1  Q2  Q3  Q4
<lambda>    8.89    9.20    7.63    7.30
<lambda>    15.77   16.19   16.93   17.59
<lambda>    -1.04   -0.95   -0.79   -0.61
...

My question is simple how to replace with 'mean', 'std', 'skew',...(I also calculate others functions) inside my chain calculation ? Before the new pandas version, the lambda function were <lambda_1>,...so I used :

.rename(index={'lambda_1': "mean"})

but now it is not possible anymore

Any idea to proceed ?

Upvotes: 0

Views: 470

Answers (2)

Jacques Tebeka
Jacques Tebeka

Reputation: 321

I also found as a solution :

data.set_axis(['mean','std'],axis='index')

and it works

Upvotes: 1

Bill Huang
Bill Huang

Reputation: 4648

Solution

List the desired row names before the pipeline:

idx_names = ["mean", "std", "skew", "kurtosis"]  # can be more

and chain this right after .agg()

.reset_index(drop=True).rename(dict(zip(range(len(idx_names)), idx_names)))

Explanation

Restore the index to [0,1,2,...] and create a dictionary that maps these numbers to the desired column names. The mapping dictionary looks like {0: "mean, 1: "std", 2: "skew", 3: "kurtosis"} in the above example.

Upvotes: 0

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