python - 根据行不适用在 Pandas 中应用

我有一个买方和助理姓名的数据框，如下所示：

df = pd.DataFrame([
{ 'buyer': 'Lebron James', 'assistant': 'Lebron James' },
{ 'buyer': 'Jon Snow', 'assistant': 'Arya Stark' },
{ 'buyer': 'Frodo Baggins', 'assistant': 'Sam Gamyi' }
])

我想将买家的名字分为他们的名字和姓氏，所以预期的输出将是：

first_name surname Lebron James Jon Snow Frodo Baggings

为此，我定义了一个函数并尝试使用apply（）：

def first_name(row):
    return df['buyer'][row].split()[0]

df['first_name'] = df.apply(first_name, axis = 1)

但是，出现以下错误：

    Traceback (most recent call last):

  File "<ipython-input-35-f3bcdf3bb991>", line 1, in <module>
    df.apply(first_name, axis = 1)

  File "/Users/javier.lopez/anaconda3/lib/python3.7/site-packages/pandas/core/frame.py", line 6487, in apply
    return op.get_result()

  File "/Users/javier.lopez/anaconda3/lib/python3.7/site-packages/pandas/core/apply.py", line 151, in get_result
    return self.apply_standard()

  File "/Users/javier.lopez/anaconda3/lib/python3.7/site-packages/pandas/core/apply.py", line 257, in apply_standard
    self.apply_series_generator()

  File "/Users/javier.lopez/anaconda3/lib/python3.7/site-packages/pandas/core/apply.py", line 286, in apply_series_generator
    results[i] = self.f(v)

  File "<ipython-input-32-410cb25f2482>", line 2, in first_name
    return df['buyer'][row].split()[0]

  File "/Users/javier.lopez/anaconda3/lib/python3.7/site-packages/pandas/core/generic.py", line 5067, in __getattr__
    return object.__getattribute__(self, name)

AttributeError: ("'Series' object has no attribute 'split'", 'occurred at index 0')

我已经了解到，使用apply with axis = 1发送了行号作为参数，所以我不明白为什么它行不通。如果我手动将行号作为参数，它将按预期工作：

first_name(1)

最佳答案

使用Series.str.split：

df1 = df['buyer'].str.split(expand=True).rename(columns={0:'first_name',1:"surname"})

print(df1)
  first_name  surname
0     Lebron    James
1        Jon     Snow
2      Frodo  Baggins

要么：

df = df.join(df1)

print(df)
      assistant          buyer first_name  surname
0  Lebron James   Lebron James     Lebron    James
1    Arya Stark       Jon Snow        Jon     Snow
2     Sam Gamyi  Frodo Baggins      Frodo  Baggins