numpy where：在哪里添加值

Question

我有这个数据框：

           ticker                   value short
0  APPL US Equity    Quarterly and Annual      
1  TTMT IN Equity    Quarterly and Annual      
2   BUD US Equity  Semi-Annual and Annual      
3    PS US Equity                  Annual      

我想要这个：

           ticker                   value short
0  APPL US Equity    Quarterly and Annual      
1  TTMT IN Equity    Quarterly and Annual      
2   BUD US Equity  Semi-Annual and Annual      
3    PS US Equity                  Annual  A    

这是我的尝试：

dfx['short'] = dfx[np.where(dfx['value'].strip() == 'Annual','A'
                                    ,dfx['short'])]

这行得通：

dfx['short'] = np.where(dfx['value'] == 'Annual','A',dfx['short'])

Answer 1

您可以使用 .loc 设置列中的部分值：

mask = dfx['value'].strip() == 'Annual'
dfx.loc[mask, 'short'] = 'A'