如何抽象两个相似的功能

Question

我有以下关于足球比赛的数据定义：

Game = namedtuple('Game', ['Date', 'Home', 'Away', 'HomeShots', 'AwayShots',
                           'HomeBT', 'AwayBT', 'HomeCrosses', 'AwayCrosses',
                           'HomeCorners', 'AwayCorners', 'HomeGoals',
                           'AwayGoals', 'HomeXG', 'AwayXG'])

这里有一些例子：

[Game(Date=datetime.date(2018, 10, 21), Home='Everton', Away='Crystal Palace', HomeShots='21', AwayShots='6', HomeBT='22', AwayBT='13', HomeCrosses='21', AwayCrosses='14', HomeCorners='10', AwayCorners='5', HomeGoals='2', AwayGoals='0', HomeXG='1.93', AwayXG='1.5'),
 Game(Date=datetime.date(2019, 2, 27), Home='Man City', Away='West Ham', HomeShots='20', AwayShots='2', HomeBT='51', AwayBT='6', HomeCrosses='34', AwayCrosses='5', HomeCorners='12', AwayCorners='2', HomeGoals='1', AwayGoals='0', HomeXG='3.68', AwayXG='0.4'),
 Game(Date=datetime.date(2019, 2, 9), Home='Fulham', Away='Man Utd', HomeShots='12', AwayShots='15', HomeBT='19', AwayBT='38', HomeCrosses='20', AwayCrosses='12', HomeCorners='5', AwayCorners='4', HomeGoals='0', AwayGoals='3', HomeXG='2.19', AwayXG='2.13'),
 Game(Date=datetime.date(2019, 3, 9), Home='Southampton', Away='Tottenham', HomeShots='12', AwayShots='15', HomeBT='13', AwayBT='17', HomeCrosses='15', AwayCrosses='15', HomeCorners='1', AwayCorners='10', HomeGoals='2', AwayGoals='1', HomeXG='2.08', AwayXG='1.27'),
 Game(Date=datetime.date(2018, 9, 22), Home='Man Utd', Away='Wolverhampton', HomeShots='16', AwayShots='11', HomeBT='17', AwayBT='17', HomeCrosses='26', AwayCrosses='13', HomeCorners='5', AwayCorners='4', HomeGoals='1', AwayGoals='1', HomeXG='0.62', AwayXG='1.12')]

还有两个几乎相同的函数计算给定球队的主客场统计数据。

def calculate_home_stats(team, games):
    """
    Calculates home stats for the given team.
    """
    home_stats = defaultdict(float)

    home_stats['HomeShotsFor'] = sum(int(game.HomeShots) for game in games if game.Home == team)
    home_stats['HomeShotsAgainst'] = sum(int(game.AwayShots) for game in games if game.Home == team)
    home_stats['HomeBoxTouchesFor'] = sum(int(game.HomeBT) for game in games if game.Home == team)
    home_stats['HomeBoxTouchesAgainst'] = sum(int(game.AwayBT) for game in games if game.Home == team)
    home_stats['HomeCrossesFor'] = sum(int(game.HomeCrosses) for game in games if game.Home == team)
    home_stats['HomeCrossesAgainst'] = sum(int(game.AwayCrosses) for game in games if game.Home == team)
    home_stats['HomeCornersFor'] = sum(int(game.HomeCorners) for game in games if game.Home == team)
    home_stats['HomeCornersAgainst'] = sum(int(game.AwayCorners) for game in games if game.Home == team)
    home_stats['HomeGoalsFor'] = sum(int(game.HomeGoals) for game in games if game.Home == team)
    home_stats['HomeGoalsAgainst'] = sum(int(game.AwayGoals) for game in games if game.Home == team)
    home_stats['HomeXGoalsFor'] = sum(float(game.HomeXG) for game in games if game.Home == team)
    home_stats['HomeXGoalsAgainst'] = sum(float(game.AwayXG) for game in games if game.Home == team)
    home_stats['HomeGames'] = sum(1 for game in games if game.Home == team)

    return home_stats


def calculate_away_stats(team, games):
    """
    Calculates away stats for the given team.
    """
    away_stats = defaultdict(float)

    away_stats['AwayShotsFor'] = sum(int(game.AwayShots) for game in games if game.Away == team)
    away_stats['AwayShotsAgainst'] = sum(int(game.HomeShots) for game in games if game.Away == team)
    away_stats['AwayBoxTouchesFor'] = sum(int(game.AwayBT) for game in games if game.Away == team)
    away_stats['AwayBoxTouchesAgainst'] = sum(int(game.HomeBT) for game in games if game.Away == team)
    away_stats['AwayCrossesFor'] = sum(int(game.AwayCrosses) for game in games if game.Away == team)
    away_stats['AwayCrossesAgainst'] = sum(int(game.HomeCrosses) for game in games if game.Away == team)
    away_stats['AwayCornersFor'] = sum(int(game.AwayCorners) for game in games if game.Away == team)
    away_stats['AwayCornersAgainst'] = sum(int(game.HomeCorners) for game in games if game.Away == team)
    away_stats['AwayGoalsFor'] = sum(int(game.AwayGoals) for game in games if game.Away == team)
    away_stats['AwayGoalsAgainst'] = sum(int(game.HomeGoals) for game in games if game.Away == team)
    away_stats['AwayXGoalsFor'] = sum(float(game.AwayXG) for game in games if game.Away == team)
    away_stats['AwayXGoalsAgainst'] = sum(float(game.HomeXG) for game in games if game.Away == team)
    away_stats['AwayGames'] = sum(1 for game in games if game.Away == team)

    return away_stats

我想知道是否有一种方法可以对这两个函数进行抽象并将它们合并为一个，而无需创建一堵 if/else 语句来确定球队是在家还是在客场比赛以及应该计算哪些字段.

Answer 1

拥有更简洁的数据结构可以编写更简单的代码。 在这种情况下，您的数据已经包含重复 （例如，您同时拥有HomeShots 和AwayShots）。

对于如何在此处构建数据有很多可能的答案。 我将讨论一个不会改变太多的解决方案 你原来的结构。

Statistics = namedtuple('Statistics', ['shots', 'BT', 'crosses', 'corners', 'goals', 'XG'])
Game = namedtuple('Game', ['home', 'away', 'date', 'home_stats', 'away_stats'])

你可以这样使用（这里我没有包括所有的统计数据，只是举几个例子）：

def calculate_stats(games, team_name, home_stats_only=False, away_stats_only=False):

    home_stats = [g.home_stats._asdict() for g in games if g.home == team_name]
    away_stats = [g.away_stats._asdict() for g in games if g.away == team_name]

    if away_stats_only:
        input_stats = away_stats
    elif home_stats_only:
        input_stats = home_stats
    else:
        input_stats = home_stats + away_stats

    def sum_on_field(field_name):
        return sum(stats[field_name] for stats in input_stats)

    return {f:sum_on_field(f) for f in Statistics._fields}

然后可以用来获取客场/主场数据：

example_game_1 = Game(
    home='Burnley', 
    away='Arsenal',
    date=datetime.now(),
    home_stats=Statistics(shots=12, BT=26, crosses=21, corners=4, goals=1, XG=1.73),
    away_stats=Statistics(shots=17, BT=26, crosses=22, corners=5, goals=3, XG=2.87),
)

example_game_2 = Game(
    home='Arsenal',
    away='Pessac',
    date=datetime.now(),
    home_stats=Statistics(shots=1, BT=1, crosses=1, corners=1, goals=1, XG=1),
    away_stats=Statistics(shots=2, BT=2, crosses=2, corners=2, goals=2, XG=2),
)

print(calculate_stats([example_game_1, example_game_2], 'Arsenal'))
print(calculate_stats([example_game_1, example_game_2], 'Arsenal', home_stats_only=True))
print(calculate_stats([example_game_1, example_game_2], 'Arsenal', away_stats_only=True))

哪些打印：

{'shots': 18, 'BT': 27, 'crosses': 23, 'corners': 6, 'goals': 4, 'XG': 3.87}
{'shots': 1, 'BT': 1, 'crosses': 1, 'corners': 1, 'goals': 1, 'XG': 1}
{'shots': 17, 'BT': 26, 'crosses': 22, 'corners': 5, 'goals': 3, 'XG': 2.87}

在处理此类数据时，通常最好使用专用工具，例如pandas。使用互动工具也很方便，比如JupyterLab。

Answer 2

我建议不要使用命名元组，而是使用带有字典的简单元组，例如：

game=(datetime.date(2019, 5, 12), 'Burnley', 'Arsenal', '12', '17', '26', '26', '21', '22', '4', '5', '1', '3', '1.73', '2.87')

还有一个映射字典：

numtostr={0: 'Date', 1: 'Home', 2: 'Away', 3: 'HomeShots', 4: 'AwayShots', 5: 'HomeBT', 6: 'AwayBT', 7: 'HomeCrosses', 8: 'AwayCrosses', 9: 'HomeCorners', 10: 'AwayCorners', 11: 'HomeGoals', 12: 'AwayGoals', 13: 'HomeXG'}
strtonum={'Date': 0, 'Home': 1, 'Away': 2, 'HomeShots': 3, 'AwayShots': 4, 'HomeBT': 5, 'AwayBT': 6, 'HomeCrosses': 7, 'AwayCrosses': 8, 'HomeCorners': 9, 'AwayCorners': 10, 'HomeGoals': 11, 'AwayGoals': 12, 'HomeXG': 13}

为 homestats 和 awaystats 制作映射字典（{0: 'HomeShotsFor', 1: 'HomeShotsAgainst' etc} for home_stats）。为了解释映射字典是如何工作的，例如，如果你想获得一个游戏的 HomeCrosses，你可以有

game[7]

或

game[strtonum['HomeCrosses']]

然后是函数：

def calculate_home_stats(team, games):
    home_stats=[0]*13
    for game in games:
        if game[1]=team:
            for index in range(12):
                home_stats[index]+=game[index+3] #because you just put the sum of everything except date, home, and away which are the first 3 indices. see how this cleans everything up?
            home_stats[12]+=1

def calculate_away_stats(team, games):
    away_stats=[0]*13
    for game in games:
        if game[2]=team:
            for index in range(12):
                away_stats[index]+=game[index+3]
            away_stats[12]+=1

如果你真的想将这两个函数合并为一个，你可以这样做：

def calculate_stats(team, games, homeaway):
    stats=[0]*13
    for game in games:
        if game[{'Home': 1, 'Away': 2}[homeaway]]=team:
            for index in range(12):
                stats[index]+=game[index+3]
            stats[12]+=1

与我的函数一样，您唯一需要更改的是检查 home 或 away 的索引，而不是需要大量更改的冗余 if else 语句。