python - 如何修改數組中的字符串？

Question

我想創建一個函數，在數組中的每個字符串前添加一個特定的單詞。最後我希望數組改變。我有這樣的代碼：

def make_great(magicians): 
    """Change magicians""" 
    for magician in magicians: 
     magician = "the Great" + magician 


magicians = ["hudini", "angel", "teller", "anderson", "copperfield"] 
make_great(magicians) 
print(magicians) 

此代碼不會更改數組。我如何讓我的功能起作用？

Answer 1

您可以在列表中使用enumerate循環用食指和價值兩，然後使用索引來直接改變值到列表：

def make_great(magicians): 
    for index, magician in enumerate(magicians): 
     magicians[index] = "the Great " + magician 

Answer 2

enumerate將是做的最好的事情這種情況下，然後修改數組中每個索引的值。

for i, magician in enumerate(magicians): 
    magicians[i] = "the Great " + magician 

Answer 3

當您使用for-each循環：

def make_great(magicians):  
    for magician in magicians: 
     magician = "The Great" + magician 

你實際上是創建一個新的字符串魔術師;因此修改它不會修改原來的數組。

相反，遍歷數組中的項目：

def make_great(magicians):  
    for i in range(len(magicians)): 
     magicians[i] = "The Great" + magicians[i] 

或者如上建議使用一個枚舉。請參閱：How to modify list entries during for loop?

Answer 4

您可以用的Python magic結合lambda和maptogether

>>> magicians = ['hudini', 'angel', 'teller', 'anderson', 'copperfield'] 
>>> map(lambda el:'pre_'+el,magicians) 
['pre_hudini', 'pre_angel', 'pre_teller', 'pre_anderson', 'pre_copperfield'] 

做到這一點試試吧here