pandas 數據處理遇到的問題
阿新 • • 發佈：2017-09-12
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數據為DataFrame格式，如下：
1.對每一行，FirstCab的值為空時，Weight的值乘以0.8
方法一（可行）：df.loc[df[‘FirstCab‘].isnull(),‘Weight‘] *= 0.8
方法二（可行）：df[‘Weight‘] = np.where(df[‘FirstCab‘].isnull(),df[‘Weight‘]*0.8,df[‘Weight‘])
方法三（不可行）：df[df[‘FirstCab‘].isnull()][‘Weight‘] *= 0.8 或者 df.loc[df[‘FirstCab‘].isnull(),:][‘Weight‘] *= 0.8
錯誤提示：A value is trying to be set on a copy of a slice from a DataFrame.Try using .loc[row_indexer,col_indexer] = value instead.
方法四（不可行）：df.assign(Weight=lambda x: x[‘Weight‘]*0.8 if x[‘FirstCab‘].isnull() else x[‘Weight‘])
或者df.assign(Weight=lambda x: x[‘Weight‘]*0.8 if x[‘FirstCab‘] == np.nan else x[‘Weight‘])
錯誤提示：ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
pandas 數據處理遇到的問題