如何颠倒Pandas系列中名字和姓氏的顺序

Question

我有一个熊猫系列：

names = pd.Series([
'Andre Agassi',
'Barry Bonds',
'Christopher Columbus',
'Daniel Defoe',
'Emilio Estevez',
'Fred Flintstone',
'Greta Garbo',
'Humbert Humbert',
'Ivan Ilych'])

它看起来像这样：

0            Andre Agassi
1             Barry Bonds
2    Christopher Columbus
3            Daniel Defoe
4          Emilio Estevez
5         Fred Flintstone
6             Greta Garbo
7         Humbert Humbert
8              Ivan Ilych

我想这样做：

0            Agassi, Andre
1             Bonds, Barry
2    Columbus, Christopher
3            Defoe, Daniel
4          Estevez, Emilio
5         Flintstone, Fred
6             Garbo, Greta
7         Humbert, Humbert
8              Ilych, Ivan

有人建议这样的代码，但它不起作用...

names.apply(split)[1]+', ' + names.apply(split)[0]

我检查了以下帖子，但它们似乎也不是我想要的：

Pandas DataFrame, how do i split a column into two

pandas: How do I split text in a column into multiple rows?

Answer 1

使用和不使用str.replace

In [451]: names.str.split().apply(lambda x: ', '.join(x[::-1]))
Out[451]:
0            Agassi, Andre
1             Bonds, Barry
2    Columbus, Christopher
3            Defoe, Daniel
4          Estevez, Emilio
5         Flintstone, Fred
6             Garbo, Greta
7         Humbert, Humbert
8              Ilych, Ivan
dtype: object

In [452]: names.apply(lambda x: ', '.join(x.split()[::-1]))
Out[452]:
0            Agassi, Andre
1             Bonds, Barry
2    Columbus, Christopher
3            Defoe, Daniel
4          Estevez, Emilio
5         Flintstone, Fred
6             Garbo, Greta
7         Humbert, Humbert
8              Ilych, Ivan
dtype: object

Answer 2

矢量化的Numpy解决方案：

In [276]: arr = names.str.split(expand=True).values[:, ::-1]

In [277]: names.values[:] = np.sum(np.insert(arr, 1, ', ', axis=1), axis=1)

In [278]: names
Out[278]:
0            Agassi, Andre
1             Bonds, Barry
2    Columbus, Christopher
3            Defoe, Daniel
4          Estevez, Emilio
5         Flintstone, Fred
6             Garbo, Greta
7         Humbert, Humbert
8              Ilych, Ivan
dtype: object

Answer 3

将.map与字符串方法结合使用，如下所示：

names.map(lambda s: s.split()[1] + ', ' + s.split()[0])