Python Pandas DataFrame-添加包含条件和的列；“以前的”；排

我有一个网球比赛结果的数据集，如下所示：

tennis_cols = ['Year','TourNo','MatchNo','Round','Winner','Loser']
tennis_rslts = [ [2018, 1, 1, 'QF', 'PlayerA', 'PlayerB']
                ,[2018, 1, 2, 'QF', 'PlayerC', 'PlayerD']
                ,[2018, 1, 3, 'QF', 'PlayerE', 'PlayerF']
                ,[2018, 1, 4, 'QF', 'PlayerG', 'PlayerH']
                ,[2018, 1, 5, 'SF', 'PlayerA', 'PlayerC']
                ,[2018, 1, 6, 'SF', 'PlayerE', 'PlayerG']
                ,[2018, 1, 7, 'F',  'PlayerA', 'PlayerE'] ]
dfTennis=pd.DataFrame(tennis_rslts,columns=tennis_cols)
dfTennis

    Year    TourNo  MatchNo Round   Winner     Loser    
0   2018    1       1       QF      PlayerA    PlayerB
1   2018    1       2       QF      PlayerC    PlayerD
2   2018    1       3       QF      PlayerE    PlayerF
3   2018    1       4       QF      PlayerG    PlayerH
4   2018    1       5       SF      PlayerA    PlayerC
5   2018    1       6       SF      PlayerE    PlayerG
6   2018    1       7       F       PlayerA    PlayerE

我想添加一列WinsToDate，其中包含本场比赛的获胜者在当前比赛之前的获胜次数，即：

    Year    TourNo  MatchNo Round   Winner     Loser    WinsToDate  
0   2018    1       1       QF      PlayerA    PlayerB  0
1   2018    1       2       QF      PlayerC    PlayerD  0 
2   2018    1       3       QF      PlayerE    PlayerF  0
3   2018    1       4       QF      PlayerG    PlayerH  0
4   2018    1       5       SF      PlayerA    PlayerC  1  <-- PlayerA won MatchNo 1
5   2018    1       6       SF      PlayerE    PlayerG  1  <-- PlayerE won MatchNo 3
6   2018    1       7       F       PlayerA    PlayerE  2  <-- PlayerA won MatchNo 1 and 5

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但这会计算所有事件，而不是当前行之前的所有事件。

奇怪的是，我要回答我自己的问题

计算WinsToDate列所需的代码是：

dfTennis['WinsToDate'] = list(map(lambda x : len(dfTennis[(dfTennis['Winner'] == dfTennis.iloc[x]['Winner']) & 
                                                          (dfTennis['MatchNo'] < dfTennis.iloc[x]['MatchNo'])]), dfTennis.index.values))

dfTennis['WinsToDate']=list（map（lambda x:len（dfTennis[（dfTennis['Winner']==dfTennis.iloc[x]['Winner']）和
（dfTennis['MatchNo']

通过将索引值传递给lambda函数，这意味着我可以访问Winner和MatchNo字段中的数据，以应用所需的逻辑

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我很高兴听到任何更好的解决方案，但这似乎适合我的需要。

@DSM答案已删除，如果您可以，请点击重复

dfTennis['WinsToDate'] = list(map(lambda x : len(dfTennis[(dfTennis['Winner'] == dfTennis.iloc[x]['Winner']) & 
                                                          (dfTennis['MatchNo'] < dfTennis.iloc[x]['MatchNo'])]), dfTennis.index.values))