困惑关于：pandas复制的数据帧警告

困惑关于：pandas复制的数据帧警告

izmir = pd.read_excel(filepath)
izmir_lim = izmir[[‘Gender’,’Age’,’MC_OLD_M>=60’,’MC_OLD_F>=60’,
‘MC_OLD_M>18’,’MC_OLD_F>18’,’MC_OLD_18>M>5’,
‘MC_OLD_18>F>5’,’MC_OLD_M_Child<5’,’MC_OLD_F_Child<5’,
‘MC_OLD_M>0<=1’,’MC_OLD_F>0<=1’,’Date to Delivery’,
‘Date to insert’,’Date of Entery’]]

izmir_lim

是的视图/副本

izmir

。随后，您尝试分配给它。这就是引发错误的原因。使用此代替：

 izmir_lim = izmir[['Gender','Age','MC_OLD_M>=60','MC_OLD_F>=60',         'MC_OLD_M>18','MC_OLD_F>18','MC_OLD_18>M>5',         'MC_OLD_18>F>5','MC_OLD_M_Child<5','MC_OLD_F_Child<5',         'MC_OLD_M>0<=1','MC_OLD_F>0<=1','Date to Delivery',         'Date to insert','Date of Entery']].copy()

每当您以下列方式从另一个“创建”新数据框时：

new_df = old_df[list_of_columns_names]

new_df

它的

is_copy

属性将具有真实值。当您尝试分配给它时，熊猫会抛出

SettingWithCopyWarning

。

new_df.iloc[0, 0] = 1  # Should throw an error

您可以通过多种方式克服这一点。

选项1

new_df = old_df[list_of_columns_names].copy()

选项2（如@ayhan在评论中建议）

new_df = old_df[list_of_columns_names]new_df.is_copy = None

选项＃3

new_df = old_df.loc[:, list_of_columns_names]