Question

我具有以下数据框，并希望将“ NaN”添加到“ DROP”列下的值“ 1”和“ 2”，并将相应的“ MEAN”列值也更改为“ NaN”。

print (df)
   Flow  DROP   MEAN
0     1   0.0  0.025
1     2   NaN    NaN
2     3   NaN    NaN
3     4   0.0  0.020

之后：

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Answer 1

在loc的条件下使用isin：

df.loc[df['DROP'].isin([1,2]), ['DROP','MEAN']] = np.nan

或通过比较不等于0的值：

df.loc[df['DROP'] != 0, ['DROP','MEAN']] = np.nan

Answer 2

您也可以使用np.where：

df['DROP'], df['MEAN'] = np.where(df.DROP != 0, np.nan, df['DROP']), np.where(df.DROP != 0, np.nan, df['MEAN'])

结果：

   Flow  DROP   MEAN
0     1   0.0  0.025
1     2   NaN    NaN
2     3   NaN    NaN
3     4   0.0  0.020

大熊猫更改列值并基于此更改另一个列值

2 个答案: