Question

我有一个df.apply，它返回一个具有键/值的序列，如下所示（我们将其称为A列）：

         Col. A
40237    1.871111
40239    1.280556
40240    1.784167
40241    0.049167
40243    0.011389
40244    0.660278
40245    1.512500

我想使用一个单独的列（B列）的值将这些值保存到各个列中。

B列可以包含6个不同的字符串（示例中为4个）。

         Col. B
40237    Open
40239    Open
40240    In Progress
40241    Closed
40243    Waiting
40244    In Progress
40245    Waiting

我想根据B列的值将A列的值保存到4列之一。

最终结果是：

         Col. A      Col. B        Open Time   In Progress Time  Closed Time Waiting Time
40237    1.871111    Open          1.871111    np.nan            np.nan      np.nan
40239    1.280556    Open          1.280556    np.nan            np.nan      np.nan
40240    1.784167    In Progress   np.nan      1.784167          np.nan      np.nan
40241    0.049167    Closed        np.nan      np.nan            0.049167    np.nan
40243    0.011389    Waiting       np.nan      np.nan            np.nan      0.011389
40244    0.660278    In Progress   np.nan      0.660278          np.nan      np.nan
40245    1.512500    Waiting       np.nan      np.nan            np.nan      1.512500

现在，我要尽最大努力做到这一点：

for key in output.index:
    df.loc[key,(df['Col. B'] + " Time")] = output.loc[key]

但是我的错误是ValueError: cannot index with vector containing NA / NaN values。我不确定为什么会这样，尽管我的专栏通常确实有很多nan。

Answer 1

将join版DataFrame中的pivot与add_suffix一起使用：

df = df.join(pd.pivot(df.index, df['Col. B'], df['Col. A']).add_suffix(' Time'))

另一种解决方案是set_index与unstack一起使用：

df = df.join(df.set_index('Col. B', append=True)['Col. A'].unstack().add_suffix(' Time'))

print (df)
         Col. A       Col. B  Closed Time  In Progress Time  Open Time  \
40237  1.871111         Open          NaN               NaN   1.871111   
40239  1.280556         Open          NaN               NaN   1.280556   
40240  1.784167  In Progress          NaN          1.784167        NaN   
40241  0.049167       Closed     0.049167               NaN        NaN   
40243  0.011389      Waiting          NaN               NaN        NaN   
40244  0.660278  In Progress          NaN          0.660278        NaN   
40245  1.512500      Waiting          NaN               NaN        NaN   

       Waiting Time  
40237           NaN  
40239           NaN  
40240           NaN  
40241           NaN  
40243      0.011389  
40244           NaN  
40245      1.512500

熊猫-有条件地存储输出

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