用其他两列替换一列中的 NaN 值

Question

我有一个由三个数据帧连接在一起的数据帧。我有变量表示它们来自哪个数据框。例如，DAY_OF_WEEK_summer1、DAY_OF_WEEK_summer2 和 DAY_OF_WEEK_summer3。一个值只能存在于这三列之一中，我想用 summer2 或 summer3 列中的值填充 DAY_OF_WEEK_summer1 中的 NaN 值。总共有 11 个这些属性我想填充 NaN 值。
这是一个示例数据框：

df = pd.DataFrame({
    'DAY_OF_WEEK_summer1': [np.nan, 'WKDY', 'SAT', np.nan, np.nan],
    'DAY_OF_WEEK_summer2': [np.nan, np.nan, np.nan, 'WKDY', 'WKDY'],
    'DAY_OF_WEEK_summer3': ['SAT', np.nan, np.nan, np.nan, np.nan],
    'ROUTE_summer1': [np.nan, 5, 6, np.nan, np.nan],
    'ROUTE_summer2': [np.nan, np.nan, np.nan, 10, 10],
    'ROUTE_summer3': [1, np.nan, np.nan, np.nan, np.nan]
})

我希望结果如下所示：

DAY_OF_WEEK_summer1  |  DAY_OF_WEEK_summer2  |  DAY_OF_WEEK_summer3  |  ROUTE_summer1 |  ROUTE_summer2   | ROUTE_summer3
---------------------+-----------------------+-----------------------+----------------+------------------+---------------
       SAT           |         NaN           |          SAT          |     1          |     NaN          |        1
       WKDY          |         NaN           |          NaN          |     5          |     NaN          |        NaN
       SAT           |         NaN           |          NaN          |     6          |     NaN          |        NaN
       WKDY          |         WKDY          |          NaN          |     10         |     10           |        NaN
       WKDY          |         WKDY          |          NaN          |     10         |     10           |        NaN

Answer 1

import numpy as np

df['DAY_OF_WEEK_summer1'] = np.where(df['DAY_OF_WEEK_summer1'].isnull(), df['DAY_OF_WEEK_summer2'], df['DAY_OF_WEEK_summer1'])
df['DAY_OF_WEEK_summer1'] = np.where(df['DAY_OF_WEEK_summer1'].isnull(), df['DAY_OF_WEEK_summer3'], df['DAY_OF_WEEK_summer1'])

用其他两列替换一列中的 NaN 值

Replace NaN values in one column from two other columns

python

nan

dataframe

pandas