在Python中替換單個元素元素

我想填充每個對象的字典，每個對象都有一個字符串列表，全部來自給定的字符串列表。問題是，當我想替換字典的單個元素時，每個元素都會改變。在Python中替換單個元素元素

Person類：

class Person: 

    messages = [] 

    def __init__(self, p): 
     self.name = p 

    def add_message(self, m_text): 
     self.messages.append(m_text)

主要代碼：

chat_messages_list = ["Eva: Eva's first text", "Eva: Eva's second text", "Eva: Eva's third text", 
         "Harry: Harry's first text", "Harry: Harry's second text", "Harry: Harry's third text", 
         "Ellis: Ellis' first text", "Ellis: Ellis' second text", "Ellis: Ellis' third text"] 
dict_persons = {} 

for element in chat_messages_list: 

    split_messages = element.split(": ") 
    name = split_messages[0] 
    message_text = split_messages[1] 

    # Create Person in list if not already exists 
    if name not in dict_persons: 
     dict_persons[name] = Person(name) 

    person = dict_persons[name] 

    # THE PROBLEM: Following line will add message_text to EVERY Person in dict_persons 
    person.add_message(message_text) 

for key, value in dict_persons.items(): 
    print("{0}: {1}".format(key, value.messages))

預期結果：

Eva: ["Eva's first text", "Eva's second text", "Eva's third text"] 
Harry: ["Harry's first text", "Harry's second text", "Harry's third text"] 
Ellis: ["Ellis' first text", "Ellis' second text", "Ellis' third text"]

實際結果：

Eva: ["Eva's first text", "Eva's second text", "Eva's third text", "Harry's first text", "Harry's second text", "Harry's third text", "Ellis' first text", "Ellis' second text", "Ellis' third text"] 
Ellis: ["Eva's first text", "Eva's second text", "Eva's third text", "Harry's first text", "Harry's second text", "Harry's third text", "Ellis' first text", "Ellis' second text", "Ellis' third text"] 
Harry: ["Eva's first text", "Eva's second text", "Eva's third text", "Harry's first text", "Harry's second text", "Harry's third text", "Ellis' first text", "Ellis' second text", "Ellis' third text"]

Wy是字符串被添加到字典中的所有對象，而不是隻是所需的一個？

來源

2017-06-14 sjorsng

是的，當然，因爲你是*附加到同一個列表*，也就是說，你添加到你在類中定義的列表中作爲'messages = []'，這是一個* class級別屬性*共享通過*所有實例*。 –

初始化messages字段Person的__init__，即self.messages = []使其成爲實例字段。
現在它是一個類級別的字段，因此所有實例共享相同的列表。

來源

2017-06-14 21:40:04 Lemx

嘗試把messages = []在您的init：

class Person: 

    def __init__(self, p): 
     self.name = p 
     self.messages = [] 

    def add_message(self, m_text): 
     self.messages.append(m_text)

這爲我工作！

來源

2017-06-14 21:38:07 cosinepenguin

在Python中替換單個元素元素

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