浅拷贝和深拷贝

a = [1,2,3,4]
print(id(a))
b = a
print(id(b))
# 地址相同
a.append('a')
print(a)
print(b)#b和a的值一致，a改变，b就跟着改变

'''
2342960103104
2342960103104
[1, 2, 3, 4, 'a']
[1, 2, 3, 4, 'a']
'''

---

浅拷贝对不可变类型和可变类型的copy不同

import copy
a = [1,2,3]
b = copy.copy(a)
a.append('a')
print(a,"   ",b)
print(id(a),id(b))
a = (1,2,3)

b = copy.copy(a)
print(id(a),id(b))
# 浅拷贝copy.copy()对于可变类型赋予的地址不同，对于不可变类型赋予相同地址

'''
[1, 2, 3, 'a']     [1, 2, 3]
2053176165376 2053176165568
2053175778688 2053175778688
'''

---

深拷贝

import copy
a = [1,2,3,4]
print(id(a))
b = copy.deepcopy(a)
print(id(b))#地址不同
a.append('a')
print(a," ",b)
# 深拷贝:不跟着拷贝的对象发生变化
'''
2944424869376
2944424869568
[1, 2, 3, 4, 'a']   [1, 2, 3, 4]
'''

---

2020-05-08