深浅拷贝

赋值

# 赋值运算， 相当于别名，贴标签，内存是一样的，你变我也变化
l = ['hi', 1, 2, 3, [4, 5, 6]]
l2 = l
print([id(x) for x in l])  # [4421400032, 4417718208, 4417718240, 4417718272, 4421841736]
print([id(x) for x in l2])  # [4421400032, 4417718208, 4417718240, 4417718272, 4421841736]
l.append('hello')
l[0] = 'nice'
print([id(x) for x in l])  # [4419514296, 4417718208, 4417718240, 4417718272, 4421841736, 4420202712]
print([id(x) for x in l2])  # [4419514296, 4417718208, 4417718240, 4417718272, 4421841736, 4420202712]
print(l)  # ['nice', 1, 2, 3, [4, 5, 6], 'hello']
print(l2)  # ['nice', 1, 2, 3, [4, 5, 6], 'hello']

浅拷贝, 更改的是不可变类型（int, str ），则拷贝的内容不跟着改变

# 浅拷贝，list1和list2的id 是不同的，但是列表中的每个元素的id是相同的
# 更改列表中的不可变类型（int, str）, 实际上是改变了ID指向，test[0]的id 由4524845296变为了4523498112
# test1[0]的id没有改变，所以值也不会改变
# 更改完test[0]的id ,test的id也没有变化, 还是4525168904
test = ['hi', 4, 5, 6, [7, 8, 9]]
test1 = test.copy()
print(id(test))  # 4525168904
print(id(test1))  # 4525266568
print([id(x) for x in test])  # [4524845296, 4522334240, 4522334272, 4522334304, 4525265736]
print([id(x) for x in test1])  # [4524845296, 4522334240, 4522334272, 4522334304, 4525265736]
test[0] = '呵'
print(id(test))   # 4525168904
print(id(test1))  # 4525266568
print([id(x) for x in test])  # [4523498112, 4522334240, 4522334272, 4522334304, 4525265736]
print([id(x) for x in test1])  # [4524845296, 4522334240, 4522334272, 4522334304, 4525265736]
print(test)  # ['呵', 4, 5, 6, [7, 8, 9]]
print(test1)  # ['hi', 4, 5, 6, [7, 8, 9]]

浅拷贝，更改的是可变的子列表，拷贝的内容则跟着改变

# 浅拷贝，list1和list2的id 是不同的，但是列表中的每个元素的id是相同的
# 更改列表只中的子列表(列表是可变的数据类型)，拷贝的内容也会变，注意子列表的id其实是没变化的为 4564984648
# 更改了list1[-1]，list1列表的id也没有变化 还是4564887816
list1 = ['hi', 1, 2, 3, [4, 5, 6]]
list2 = list1.copy()
print(id(list1))  # 4564887816
print(id(list2))  # 4564985480
print([id(x) for x in list1])  # [4564542944, 4560861120, 4560861152, 4560861184, 4564984648]
print([id(x) for x in list2])  # [4564542944, 4560861120, 4560861152, 4560861184, 4564984648]
print(list1)  # ['hi', 1, 2, 3, [4, 5, 6]]
print(list2)  # ['hi', 1, 2, 3, [4, 5, 6]]
list1[-1].append('4')
print(list1)  # ['hi', 1, 2, 3, [4, 5, 6, '4']]
print(list2)  # ['hi', 1, 2, 3, [4, 5, 6, '4']]
print([id(x) for x in list1])  # [4564542944, 4560861120, 4560861152, 4560861184, 4564984648]
print([id(x) for x in list2])  # [4564542944, 4560861120, 4560861152, 4560861184, 4564984648]
print(id(list1))  # 4564887816
print(id(list2))  # 4564985480

深拷贝：改变的是可变的数据类型,深拷贝是你变我不变, 对于列表中嵌套的列表，拷贝后的嵌套列表id 是不同的

# 深拷贝：对于不可变的数据类型（int string等), 为节省空间，id 是相同的 4562511328, 4558849984, 4558850016, 4558850048
# 对于可变的数据类型（如list），拷贝的id是不同的
# 深拷贝改变可变的数据类型（如嵌套列表l[4]）, 则拷贝的内容不会改变
# 更改了子元素，原始数组l的id 值没有改变，依然为4562953544
import copy
# 深浅拷贝
l = ['hi', 1, 2, 3, [4, 5, 6]]
l1 = copy.deepcopy(l)
print(l)  # ['hi', 1, 2, 3, [4, 5, 6]]
print(l1)  # ['hi', 1, 2, 3, [4, 5, 6]]
print(id(l))  # 4562953544
print(id(l1))  # 4562953288
print([id(x) for x in l])  # [4562511328, 4558849984, 4558850016, 4558850048, 4562953608]
print([id(x) for x in l1])  # [4562511328, 4558849984, 4558850016, 4558850048, 4562909128]
l[4].append('hello')
print(l)  # ['hi', 1, 2, 3, [4, 5, 6, 'hello']]
print(l1)  # ['hi', 1, 2, 3, [4, 5, 6]]
print(id(l))  # 4562953544
print(id(l1))  # 4562953288

深拷贝：更改不可变数据类型，实际行是指向变化了，开辟了个新的内存。

# 
# 深拷贝：可变的数据类型，拷贝之后id不同
import copy
# 深浅拷贝
l = ['hi', 1, 2, 3, [4, 5, 6]]
l1 = copy.deepcopy(l)
print(l)  # ['hi', 1, 2, 3, [4, 5, 6]]
print(l1)  # ['hi', 1, 2, 3, [4, 5, 6]]
print(id(l))  # 4426221128
print(id(l1))  # 4426221000
print([id(x) for x in l])  # [4425779440, 4422096832, 4422096864, 4422096896, 4426221192]
print([id(x) for x in l1])  # [4425779440, 4422096832, 4422096864, 4422096896, 4426220936]
l[0] = ['hello']
print(l)  # [['hello'], 1, 2, 3, [4, 5, 6]]
print(l1)  # ['hi', 1, 2, 3, [4, 5, 6]]
print(id(l))  # 4426221128
print(id(l1)) # 4426221000
print([id(x) for x in l])  # [4426220872, 4422096832, 4422096864, 4422096896, 4426221192]
print([id(x) for x in l1]) # [4425779440, 4422096832, 4422096864, 4422096896, 4426220936]

浅拷贝：list dic : 嵌套的可变的数据类型id是同一个，你变我也变

深拷贝：list dic :嵌套的可变的数据类型id不是同一个，你变我不变

l1 = [1, 2, 3, [22, 33]]
l2 = l1[:]
l1[3].append(666)
print(l1)  # [1, 2, 3, [22, 33, 666]]
print(l2)  # [1, 2, 3, [22, 33, 666]] 你变我也变，证明切片是浅拷贝