如何对两个相似的函数进行抽象

问题描述 投票：0回答：2

我具有关于足球比赛的以下数据定义：

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功能，用于计算给定团队的主场和客场统计。

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功能进行抽象，然后将它们合并为一个功能，而无需创建if / else语句围墙来确定团队是在主场还是不在场，以及应该计算哪些字段。

python python-3.x dry abstraction
2个回答
1
投票

具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项（例如，您同时拥有HomeShots和AwayShots。）>

这里有许多可能的结构答案。我将介绍一个不会带来太大变化的解决方案您的原始结构。

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

您可以这样使用（我这里没有包括所有统计信息，仅举几个例子）：
def calculate_stats(games, away=False):

    def team_stats(game, field_name):
        if away:
            stats = game.away_stats
        else:
            stats = game.home_stats
        return stats._asdict()[field_name]

    def sum_on_field(field_name):
        return sum(team_stats(g, field_name) for g in games)

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

然后可以用来同时获得离开/本垒打的统计：

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='Burnley', 
    away='Arsenal',
    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),
)

home_stats = calculate_stats([example_game_1, example_game_2])
away_stats = calculate_stats([example_game_1, example_game_2], away=True)

print(home_stats)
print(away_stats)

哪些印刷品：
{'shots': 13, 'BT': 27, 'crosses': 22, 'corners': 5, 'goals': 2, 'XG': 2.73}
{'shots': 19, 'BT': 28, 'crosses': 24, 'corners': 7, 'goals': 5, 'XG': 4.87}

[处理此类数据时，通常最好使用专用工具，例如pandas。使用交互式工具（例如JupyterLab）也可能非常方便。

例如，我不建议使用命名元组，而是带字典的简单元组：

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

和一个映射字典：

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'等}表示home_stats）。为了解释映射词典的工作原理，例如，如果您想获得游戏的HomeCrosses，可以使用

game[7]

或

game[strtonum['HomeCrosses']]

然后功能：

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

如果您真的想将两个功能合并为一个，则可以执行此操作：

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原点或原点的索引，而不是需要大量更改的多余的if else语句。

0
投票

例如，我不建议使用命名元组，而是带字典的简单元组：

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