我正在嘗試根據(jù)從其他列和行中搜索數(shù)據(jù)在數(shù)據(jù)框中創(chuàng)建新列。計(jì)算此類列值的最佳/禁食方法是什么。我嘗試過使用 lambda 和外部函數(shù)，但沒有結(jié)果。有人可以詳細(xì)說明獲得最終結(jié)果的方法以及從計(jì)算時間來看哪種方法是最佳的。我們可以分配函數(shù)/lambda 來計(jì)算這些值嗎？我們可以實(shí)現(xiàn)數(shù)據(jù)框，它會保持引用函數(shù)計(jì)算列中的值而不是計(jì)算值本身嗎？基于其他列/行中的數(shù)據(jù)的動態(tài)結(jié)果。data = { 'ID':[1, 2, 3, 4 ,5], 'Name':['Andy', 'Rob', 'Tony', 'John', 'Lui'], 'M_Name':['Lui', 'Lui', 'Lui','NoData', 'John'] } df = pd.DataFrame(data) Original DataFrame: ID M_Name Name0 1 Lui Andy1 2 Lui Rob2 3 Lui Tony3 4 NoData John4 5 John Luidata_after = { 'ID':[1, 2, 3, 4 ,5], 'Name':['Andy', 'Rob', 'Tony', 'John', 'Lui'], 'M_Name':['Lui', 'Lui', 'Lui','NoData', 'John'], 'ID_by_M_Name':[5, 5, 5, 'NoData', '4'] } df1 = pd.DataFrame(data_after)Processed DataFrame: ID ID_by_M_Name M_Name Name0 1 5 Lui Andy1 2 5 Lui Rob2 3 5 Lui Tony3 4 NoData NoData John4 5 4 John LuiI have tried two ways to get ID but not sure how to use them in assigngetID = lambda name: df.loc[df['Name'] == name]['ID'].iloc[0]def mID(name): return df.loc[df['Name'] == name]['ID'].iloc[0]For each row we want to find ID of M_Name for specifc Name. e.g. for Name='Andy' we have M_Name = 'Lui' and Lui's ID(5)For Lui M_name is John and John's ID is 4print(getID('Lui'))print(mID('Lui'))df['ID'] = df.assign(mID(df['M_Name']), axis=1 )IndexError：單個位置索引器超出范圍
1 回答
森欄
TA貢獻(xiàn)1810條經(jīng)驗(yàn) 獲得超5個贊
使用Series.replaceor ：Series.map_Series.fillna
df['ID_by_M_Name'] = df['M_Name'].replace(df.set_index('Name')['ID'])
#assign alternative
#df = df.assign(ID_by_M_Name = df['M_Name'].replace(df.set_index('Name')['ID']))
df['ID_by_M_Name'] = df['M_Name'].map(df.set_index('Name')['ID']).fillna(df['M_Name'])
#assign alternative
#df=df.assign(ID_by_M_Name=df['M_Name'].map(df.set_index('Name')['ID']).fillna(df['M_Name']))
print (df)
ID Name M_Name ID_by_M_Name
0 1 Andy Lui 5
1 2 Rob Lui 5
2 3 Tony Lui 5
3 4 John NoData NoData
4 5 Lui John 4
如果新列的重要位置使用DataFrame.insert：
df.insert(1, 'ID_by_M_Name', df['M_Name'].replace(df.set_index('Name')['ID']))
print (df)
ID ID_by_M_Name Name M_Name
0 1 5 Andy Lui
1 2 5 Rob Lui
2 3 5 Tony Lui
3 4 NoData John NoData
4 5 4 Lui John
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