Question

我是熊猫新手。我有一个Horse结果数据框，看起来像这样（只有大得多）：

    Horses        RaceDate Position
1   RedHorse      1/2/00   2
2   BlueHorse     1/2/00   6
3   YellowHorse   1/2/00   7
4   RedHorse      15/1/00  1
5   RedHorse      1/1/00   5

对于每个条目，我想计算出那匹马第一次跑的赢率。像这样：

    Horses        RaceDate Position WinPercentage
1   RedHorse      1/2/00   2        50%    
2   BlueHorse     1/2/00   6        0%
3   YellowHorse   1/2/00   7        0%
4   RedHorse      15/1/00  5        100%
5   RedHorse      1/1/00   1        0%

我该怎么做？

Answer 1

每匹马获胜

df2 = df.copy(deep=True)
df2 = df2.reset_index()
df2 = df2.sort_values('RaceDate')
df2['win'] = np.where(df2.Position == 1, 1, 0)
df2['win_count'] = df2.groupby(['Horses'])['win'].cumsum()
df2['race_count'] = df2.groupby(['Horses'])['win_count'].cumsum()
df2['WinPercentage'] = df2['win_count'] / df2['race_count'] * 100
df2 = df2.sort_index()
print(df2)

输出：

   index       Horses   RaceDate  Position  win  win_count  race_count  WinPercentage
0      1     RedHorse 2000-02-01         2    0          1           2           50.0
1      2    BlueHorse 2000-02-01         6    0          0           0            NaN
2      3  YellowHorse 2000-02-01         7    0          0           0            NaN
3      4     RedHorse 2000-01-15         1    1          1           1          100.0
4      5     RedHorse 2000-01-01         5    0          0           0            NaN

每行获胜

df1 = df.copy(deep=True)
df1 = df1.reset_index()
df1 = df1.sort_values(['RaceDate', 'index'])
df1['win'] = np.where(df1.Position == 1, 1, 0)
df1['win'] = df1.win.ffill()
df1['win_count'] = df1.win.cumsum()
df1['race_count'] = df1.win_count.cumsum()
df1['WinPercentage'] = df1['win_count'] / df1['race_count'] * 100
print(df1)

输出：

   index       Horses   RaceDate  Position  win  win_count  race_count  WinPercentage
4      5     RedHorse 2000-01-01         5    0          0           0            NaN
3      4     RedHorse 2000-01-15         1    1          1           1     100.000000
0      1     RedHorse 2000-02-01         2    0          1           2      50.000000
1      2    BlueHorse 2000-02-01         6    0          1           3      33.333333
2      3  YellowHorse 2000-02-01         7    0          1           4      25.000000

两个数据框的串联

dfFinal = df1[['index', 'Horses', 'RaceDate', 'WinPercentage']].merge(df2[['index', 'Horses', 'RaceDate', 'WinPercentage']], on=['index', 'Horses', 'RaceDate'], how='outer')
print(dfFinal)

输出：

   index       Horses   RaceDate  WinPercentage_x  WinPercentage_y
0      5     RedHorse 2000-01-01              NaN              NaN
1      4     RedHorse 2000-01-15       100.000000            100.0
2      1     RedHorse 2000-02-01        50.000000             50.0
3      2    BlueHorse 2000-02-01        33.333333              NaN
4      3  YellowHorse 2000-02-01        25.000000              NaN

Answer 2

如果我对您的理解正确，那么您需要按日期排序，按马分组，然后取每个日期获胜的累计均值？

df['WonRace'] = df['Position'] == 1
df.sort_values('RaceDate').groupby('Horses')['WonRace'].expanding().mean()

熊猫-在数据框中创建滚动百分比

2 个答案: