有时候需要对 pandas Series 里的值进行一些操作,但是没有内置函数,这时候可以自己写一个函数,使用 pandas Series 的 apply 方法,可以对里面的每个值都调用这个函数,然后返回一个新的 Series
import pandas as pd s = pd.Series([1, 2, 3, 4, 5])
def add_one(x):
return x + 1 print s.apply(add_one) # 结果:
0 2
1 3
2 4
3 5
4 6
dtype: int64
一个栗子:
names = pd.Series([
'Andre Agassi',
'Barry Bonds',
'Christopher Columbus',
'Daniel Defoe',
'Emilio Estevez',
'Fred Flintstone',
'Greta Garbo',
'Humbert Humbert',
'Ivan Ilych',
'James Joyce',
'Keira Knightley',
'Lois Lane',
'Mike Myers',
'Nick Nolte',
'Ozzy Osbourne',
'Pablo Picasso',
'Quirinus Quirrell',
'Rachael Ray',
'Susan Sarandon',
'Tina Turner',
'Ugueth Urbina',
'Vince Vaughn',
'Woodrow Wilson',
'Yoji Yamada',
'Zinedine Zidane'
])
把以上Series里的名字从"Firstname Lastname" 转换成 "Lastname, FirstName"
可以使用apply方法:
def reverse_name(name):
name_array = name.split(' ') new_name = '{}, {}'.format(name_array[1],name_array[0])
return new_name print(names.apply(reverse_name))
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
9 Joyce, James
10 Knightley, Keira
11 Lane, Lois
12 Myers, Mike
13 Nolte, Nick
14 Osbourne, Ozzy
15 Picasso, Pablo
16 Quirrell, Quirinus
17 Ray, Rachael
18 Sarandon, Susan
19 Turner, Tina
20 Urbina, Ugueth
21 Vaughn, Vince
22 Wilson, Woodrow
23 Yamada, Yoji
24 Zidane, Zinedine
dtype: object