将ifelse函数应用于python/pandas中的两个字符串列

html5 • • 问答

在我的数据框中，我有：

Name    Sex    Height
Jackie   F       Small
John     M       Tall

我已将以下函数应用于创建基于组合的新列：

def genderfunc(x,y):
    if x =='Tall' & y=='M':
        return 'T Male'
    elif x =='Medium' & y=='M':
        return 'Male'
    elif x =='Small' & y=='M':
        return 'Male'
    elif x =='Tall' & y=='F':
        return 'T Female'
    elif x =='Medium' & y=='F':
        return 'Female'
    elif x =='Small' & y=='F':
        return 'Female'
    else:
        return y

我应用此函数的代码行：

df['GenderDetails'] = df.apply(genderfunc(df['Height'],df['Sex']))

我得到以下信息：

类型错误：无法使用 dtyped [object] 数组和 [bool] 类型的标量执行“rand_”

关于我在这里做错了什么的任何想法？这是我第一次使用函数。

谢谢！

回答

这是另一种方法，使用map.

map_ = {"TallM": "T Male", "SmallF": "Female"}

df['GenderDetails'] = (df['Height'] + df['Sex']).str.strip().map(map_)

     Name Sex Height GenderDetails
0  Jackie   F  Small        Female
1    John   M   Tall        T Male

回答

或者你可以使用 np.select，如果性能是一个问题-

condlist = [(df['Height'] == 'Tall') & (df['Sex'] == 'M'),
            (df['Height'] == 'Medium') & (df['Sex'] == 'M'),
            (df['Height'] == 'Small') & (df['Sex'] == 'M'),
            (df['Height'] == 'Tall') & (df['Sex'] == 'F'),
            (df['Height'] == 'Medium') & (df['Sex'] == 'F'),
            (df['Height'] == 'Small') & (df['Sex'] == 'F')]
choiselist = [
    'T Male',
    'Male',
    'Male',
    'T Female',
    'Female',
    'Female'
]

df['GenderDetails'] = np.select(condlist, choiselist, df['Sex'])

以上是将ifelse函数应用于python/pandas中的两个字符串列的全部内容。
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