pandas dataframe - Python 中的多個 if 條件

Question

我正在關注這個問題的答案

我有一個這樣的df ：

score_1   score_2  
1.11        NaN      
2.22        3.33      
NaN         3.33      
NaN         NaN
........       

計算final_score的規則是，我們要求至少有一個分數是non-null ，如果 NULL 中的一個分數，那么 final_score 將等於另一個分數（它具有所有權重）這是要復制的代碼：

import numpy as np
import pandas as pd

df = pd.DataFrame({
            'score_1': [1.11, 2.22, np.nan],
            'score_2': [np.nan, 3.33, 3.33]
        })

def final_score(df):
    if (df['score_1'] != np.nan) and (df['score_2'] != np.nan):
        print('I am condition one')
        return df['score_1'] * 0.2 + df['score_2'] * 0.8

    elif (df['score_1'] == np.nan) and (df['score_2'] != np.nan):
        print('I am the condition two')
        return df['score_2']

    elif (df['score_1'] != np.nan) and (df['score_2'] == np.nan):
        print('I am the condition three')
        return df['score_1']

    elif (df['score_1'] == np.nan) and (df['score_2'] == np.nan):
        print('I am the condition four')
        return np.nan

df['final_score'] = df.apply(final_score, axis=1)
print(df)

這給了我 output：

score_1   score_2  final_score
1.11        NaN       NaN
2.22        3.33      3.108
NaN         3.33      NaN
NaN         NaN       NaN
........ 

但我預期的 output 如下：

score_1   score_2  final_score
1.11        NaN       1.11
2.22        3.33      3.108
NaN         3.33      3.33
NaN         NaN       NaN
........ 

第一行和第三行不是我期望的結果，有人可以幫助我，我的代碼有什么問題嗎？ 非常感謝。

Answer 1

讓我們使用 np.where 應用您的條件

df['final_score'] =np.where(df.notna().all(1),df['score_1'] * 0.2 + df['score_2'] * 0.8,df.mean(1))



   score_1  score_2  final_score
0     1.11      NaN        1.110
1     2.22     3.33        3.108
2      NaN     3.33        3.330
3      NaN      NaN          NaN

Answer 2

使用 np.isnan() 進行比較應該可以解決問題