[python] plot the values ​​before and after the conversion of yeojohnson conversion

import numpy as np
import pandas as pd

#Copy the formula here
# https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.yeojohnson.html
def yeojohnson(lmbda, x):
    if x >= 0 and lmbda != 0:
        y = ((x + 1)**lmbda - 1) / lmbda
    
    elif x >= 0 and lmbda == 0:
        y = np.log(x + 1)
    
    elif x < 0 and lmbda != 2:
        y = -((-x + 1)**(2 - lmbda) - 1) / (2 - lmbda)
        
    elif x < 0 and lmbda == 2:
        y = -np.log(-x + 1)
    
    else:
        #Should not reach
        raise
    
    return y

#Value to convert
x_ary = np.arange(21)-10

#Try a combination of two patterns of lmbda
for lmbda_ary in [np.arange(10)*0.25, np.arange(10)*0.5]:
    
    #Convert and combine into df
    X_dic = {}
    for lmbda in lmbda_ary:
        X_dic[lmbda] = [yeojohnson(lmbda, float(x)) for x in x_ary]
    df = pd.DataFrame(X_dic, index=x_ary)
    
    #drawing
    df.plot(cmap='viridis', marker='.')
    plt.xlabel('Original value (x)')
    plt.ylabel('Converted value (y)')
    plt.title('Change in value after conversion when lmbda is changed')
    plt.show()

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