本文由 Luzhuo 编写,转发请保留该信息. 原文: http://blog.csdn.net/Rozol/article/details/71156387
以下代码以Python3.6.1为例 Less is more!
#!/usr/bin/env python # coding=utf-8 __author__ = 'Luzhuo' __date__ = '2017/5/3' # copydemo.py copy深和浅拷贝 # 深浅拷贝区别: # 1.浅拷贝:创建新的复合对象，然后将'引用'拷贝到该复合对象中。 # 2.深拷贝:创建新的复合对象，然后'递归地将原始对象'拷贝到该复合对象中 import copy class Ls: def __init__(self, name): self.name = name @property def setname(self, name): self.name = name def __str__(self): return self.name __repr__ = __str__ def __iter__(self): return self list_0 = ["A", "B", ["C", "D"], Ls("E")] def demo(): # --- 浅拷贝的拷贝方式 --- list_1 = copy.copy(list_0) list_2 = list_0.copy() list_3 = list_0[:] list_4 = list(list_0) # --- 深拷贝的拷贝方式 --- lists_d = copy.deepcopy(list_0) # --- 深浅拷贝的区别 --- # 1. 对第一层数据进行赋值 list_0[0] = "X0" list_1[0] = "X1" list_2[0] = "X2" list_3[0] = "X3" list_4[0] = "X4" lists_d[0] = "Xd" # 打印结果: 理所当然,所有列表都发生了变化 # list_0: ['X0', 'B', ['C', 'D'], E] # list_1: ['X1', 'B', ['C', 'D'], E] # list_2: ['X2', 'B', ['C', 'D'], E] # list_3: ['X3', 'B', ['C', 'D'], E] # list_4: ['X4', 'B', ['C', 'D'], E] # list_d: ['Xd', 'B', ['C', 'D'], E] # 2. 对第二层的list引用进行赋值 list_0[2][0] = "Y0" list_1[2][0] = "Y1" list_2[2][0] = "Y2" list_3[2][0] = "Y3" list_4[2][0] = "Y4" lists_d[2][0] = "Yd" # 打印结果: 0-1都被改成了同一个值,这说明浅拷贝只拷贝了第二层list的引用;而深拷贝则拷贝了数据结构 # list_0: ['X0', 'B', ['Y4', 'D'], E] # list_1: ['X1', 'B', ['Y4', 'D'], E] # list_2: ['X2', 'B', ['Y4', 'D'], E] # list_3: ['X3', 'B', ['Y4', 'D'], E] # list_4: ['X4', 'B', ['Y4', 'D'], E] # list_d: ['Xd', 'B', ['Yd', 'D'], E] # 3. 对第三层的Ls对象引用进行赋值 list_0[3].name = "Z0" list_1[3].name = "Z1" list_2[3].name = "Z2" list_3[3].name = "Z3" list_4[3].name = "Z4" lists_d[3].name = "Zd" # 执行结果: 继续验证了上方论点 # list_0: ['X0', 'B', ['Y4', 'D'], Z4] # list_1: ['X1', 'B', ['Y4', 'D'], Z4] # list_2: ['X2', 'B', ['Y4', 'D'], Z4] # list_3: ['X3', 'B', ['Y4', 'D'], Z4] # list_4: ['X4', 'B', ['Y4', 'D'], Z4] # list_d: ['Xd', 'B', ['Yd', 'D'], Zd] print("list_0: {}".format(list_0)) print("list_1: {}".format(list_1)) print("list_2: {}".format(list_2)) print("list_3: {}".format(list_3)) print("list_4: {}".format(list_4)) print("list_d: {}".format(lists_d)) if __name__ == "__main__": demo()