【Python】引用、浅拷贝、深拷贝

定义

    可变对象常见类型： list,dict,set,bytearray　　（可变对象内存地址不会发生变化（id() 获取内存地址））

不可变对象常见类型：int,str,bool,float,None,tuple,bytes,frozenset

    a = 3   # int 不可变对象
    b = [1, 2]  # list 可变对象
    print("a = {}; b = {}".format(a, b))
    print("改变前：a = {}, b = {}".format(id(a), id(b)))
    a = a+1
    b.append(a)
    print("a = {}; b = {}".format(a, b))
    print("改变后：a = {}, b = {}".format(id(a), id(b)))

 

执行结果：　　

 

引用、浅拷贝、深拷贝

引用：内存地址相同，子对象内存地址相同 (修改子对象 会 影响原数据)

浅拷贝：内存地址不同，可变子对象内存地址相同（修改可变子对象 会 影响原数据）；不可变子对象内存地址不同（修改后不影响原数据）

深拷贝：内存地址不同，可变及不可变子对象内存地址不同（修改子对象数据 不会 影响原数据）

 

 

    x = ["a", "b", "c", [1, 2, 3]]
    a = x
    b = copy.copy(x)
    c = copy.deepcopy(x)
    print("原始数据：x = {}, \n\t赋值给a = {} \n\t浅拷贝b = {} \n\t深拷贝c = {}".format(x, a, b, c))
    print("内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x), id(a), id(b), id(c)))
    print("子对象内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x[3]), id(a[3]), id(b[3]), id(c[3])))
    # x[3].append(4)
    b[3].append(4)
    c[3].append(88888)
    print("")
    print(">>> 原数据/浅拷贝 修改可变子对象：：：影响原数据; 深拷贝修改可变子对象：：：不影响原数据")
    print("原始数据：x = {}, \n\t赋值给a = {} \n\t浅拷贝b = {} \n\t深拷贝c = {}".format(x, a, b, c))
    print("内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x), id(a), id(b), id(c)))
    print("子对象内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x[3]), id(a[3]), id(b[3]), id(c[3])))

    b[2] = "cc"
    c[1] = "bb"
    print("")
    print(">>> 原数据/浅拷贝 修改不可变子对象；")
    print("原始数据：x = {}, \n\t赋值给a = {} \n\t浅拷贝b = {} \n\t深拷贝c = {}".format(x, a, b, c))
    print("内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x), id(a), id(b), id(c)))
    print("子对象内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x[1]), id(a[1]), id(b[1]), id(c[1])))
    print("子对象内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x[2]), id(a[2]), id(b[2]), id(c[2])))

 

 

 

 执行结果：

 

 

 

 

    x = ["a", "b", "c", [1, 2, 3]]
    a = x
    b = copy.copy(x)
    c = copy.deepcopy(x)
    print("原始数据：x = {}, \n\t赋值给a = {} \n\t浅拷贝b = {} \n\t深拷贝c = {}".format(x, a, b, c))
    print("内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x), id(a), id(b), id(c)))
    print("子对象内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x[3]), id(a[3]), id(b[3]), id(c[3])))
    # x[3].append(4)
    a.append("a")
    b[3].append(4)
    c[3].append(88888)
    print("")
    print(">>> 原数据/浅拷贝 修改可变子对象：：：影响原数据; 深拷贝修改可变子对象：：：不影响原数据")
    print("原始数据：x = {}, \n\t赋值给a = {} \n\t浅拷贝b = {} \n\t深拷贝c = {}".format(x, a, b, c))
    print("内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x), id(a), id(b), id(c)))
    print("子对象内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x[3]), id(a[3]), id(b[3]), id(c[3])))
    a[0] = "aa"
    b[2] = "cc"
    c[1] = "bb"
    print("")
    print(">>> 原数据/浅拷贝 修改不可变子对象；")
    print("原始数据：x = {}, \n\t赋值给a = {} \n\t浅拷贝b = {} \n\t深拷贝c = {}".format(x, a, b, c))
    print("内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x), id(a), id(b), id(c)))
    print("子对象内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x[1]), id(a[1]), id(b[1]), id(c[1])))
    print("子对象内存地址：x = {}, \t赋值给a = {} \t浅拷贝b = {} \t深拷贝c = {}".format(id(x[2]), id(a[2]), id(b[2]), id(c[2])))

 

原始数据：x = ['a', 'b', 'c', [1, 2, 3]], 
    赋值给a = ['a', 'b', 'c', [1, 2, 3]] 
    浅拷贝b = ['a', 'b', 'c', [1, 2, 3]] 
    深拷贝c = ['a', 'b', 'c', [1, 2, 3]]
内存地址：x = 81173896,     赋值给a = 81173896     浅拷贝b = 81202504     深拷贝c = 81202440
子对象内存地址：x = 81202696,     赋值给a = 81202696     浅拷贝b = 81202696     深拷贝c = 81202088

>>> 原数据/浅拷贝 修改可变子对象：：：影响原数据; 深拷贝修改可变子对象：：：不影响原数据
原始数据：x = ['a', 'b', 'c', [1, 2, 3, 4], 'a'], 
    赋值给a = ['a', 'b', 'c', [1, 2, 3, 4], 'a'] 
    浅拷贝b = ['a', 'b', 'c', [1, 2, 3, 4]] 
    深拷贝c = ['a', 'b', 'c', [1, 2, 3, 88888]]
内存地址：x = 81173896,     赋值给a = 81173896     浅拷贝b = 81202504     深拷贝c = 81202440
子对象内存地址：x = 81202696,     赋值给a = 81202696     浅拷贝b = 81202696     深拷贝c = 81202088

>>> 原数据/浅拷贝 修改不可变子对象；
原始数据：x = ['aa', 'b', 'c', [1, 2, 3, 4], 'a'], 
    赋值给a = ['aa', 'b', 'c', [1, 2, 3, 4], 'a'] 
    浅拷贝b = ['a', 'b', 'cc', [1, 2, 3, 4]] 
    深拷贝c = ['a', 'bb', 'c', [1, 2, 3, 88888]]
内存地址：x = 81173896,     赋值给a = 81173896     浅拷贝b = 81202504     深拷贝c = 81202440
子对象内存地址：x = 45594528,     赋值给a = 45594528     浅拷贝b = 45594528     深拷贝c = 81548032
子对象内存地址：x = 45504832,     赋值给a = 45504832     浅拷贝b = 81548000     深拷贝c = 45504832