pandas數組(pandas Series)-(5)apply方法自訂函數

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有時候需要對 pandas Series 裡的值進行一些操作,但是沒有內建函數,這時候可以自己寫一個函數,使用 pandas Series 的 apply 方法,可以對裡面的每個值都調用這個函數,然後返回一個新的 Series 

import pandas as pds = pd.Series([1, 2, 3, 4, 5])def add_one(x):    return x + 1print s.apply(add_one)# 結果:0    21    32    43    54    6dtype: int64

 

一個栗子:

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裡的名字從"Firstname Lastname" 轉換成 "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_nameprint(names.apply(reverse_name))

0             Agassi, Andre1              Bonds, Barry2     Columbus, Christopher3             Defoe, Daniel4           Estevez, Emilio5          Flintstone, Fred6              Garbo, Greta7          Humbert, Humbert8               Ilych, Ivan9              Joyce, James10         Knightley, Keira11               Lane, Lois12              Myers, Mike13              Nolte, Nick14           Osbourne, Ozzy15           Picasso, Pablo16       Quirrell, Quirinus17             Ray, Rachael18          Sarandon, Susan19             Turner, Tina20           Urbina, Ugueth21            Vaughn, Vince22          Wilson, Woodrow23             Yamada, Yoji24         Zidane, Zinedinedtype: object

 

pandas數組(pandas Series)-(5)apply方法自訂函數