Question

我有一个数据框

        game_id  move_number  move      colour  avg_centi   phase
    0   03gDhPWr    1         e4        white   NaN         opening
    1   03gDhPWr    2         d5        black   37.0        opening
    2   03gDhPWr    3         e5        white   61.0        opening
    3   03gDhPWr    4         c5        black   -5.0        opening
    4   03gDhPWr    5         Nf3       white   26.0        opening
... ... ... ... ... ... ...
110093  zzaiRa7s    36        a5+       black   NaN         endgame
110094  zzaiRa7s    37        Kxb5      white   NaN         endgame
110095  zzaiRa7s    38        c6+       black   NaN         endgame
110096  zzaiRa7s    39        Ka4       white   NaN         endgame
110097  zzaiRa7s    40        Q@b4#     black   NaN         endgame

我想映射colour列，以便在颜色为black时将colour列的值替换为phase列中的值。我想使用熊猫map或apply函数来理想地做到这一点。不是replace，这太慢了。

结果数据框应如下所示：

game_id move_number move        colour  avg_centi   phase
    0   03gDhPWr    1   e4      white   NaN         opening
    1   03gDhPWr    2   d5      opening 37.0        opening
    2   03gDhPWr    3   e5      white   61.0        opening
    3   03gDhPWr    4   c5      opening -5.0        opening
    4   03gDhPWr    5   Nf3     white   26.0        opening
... ... ... ... ... ... ...
110093  zzaiRa7s    36  a5+     endgame NaN         endgame
110094  zzaiRa7s    37  Kxb5    white   NaN         endgame
110095  zzaiRa7s    38  c6+     engame  NaN         endgame
110096  zzaiRa7s    39  Ka4     white   NaN         endgame
110097  zzaiRa7s    40  Q@b4#   endgame NaN         endgame

我尝试了以下代码，但似乎不太起作用：

def wrangle_game_phase(x):
    if x == 'black':
        return phase
    else:
        return x

df['game_type'] = df['colour'].apply(wrangle_game_phase)

Answer 1

对pd.DataFrame.loc使用布尔索引：

m = df['colour'] == 'black'
df.loc[m, 'colour'] = df.loc[m, 'phase']
         game_id  move_number   move   colour  avg_centi    phase
0       03gDhPWr            1     e4    white        NaN  opening
1       03gDhPWr            2     d5  opening       37.0  opening
2       03gDhPWr            3     e5    white       61.0  opening
3       03gDhPWr            4     c5  opening       -5.0  opening
4       03gDhPWr            5    Nf3    white       26.0  opening
110093  zzaiRa7s           36    a5+  endgame        NaN  endgame
110094  zzaiRa7s           37   Kxb5    white        NaN  endgame
110095  zzaiRa7s           38    c6+  endgame        NaN  endgame
110096  zzaiRa7s           39    Ka4    white        NaN  endgame
110097  zzaiRa7s           40  Q@b4#  endgame        NaN  endgame

Answer 2

使用np.where

例如：：

df['game_type'] = np.where(df["colour"] == 'black', df["phase"], df["colour"])

Answer 3

您尝试过.loc吗？请尝试：

df.loc[df['Color'] =='Black', 'Color'] = df['Phase']

熊猫根据条件将一列映射到另一列

3 个答案: