1. python中赋值
a = [3,6,9,4,7]
b = a
此时b和a指向同一内存地址，如果a中元素发生变化,b中也会发生变化。如
a[0]=4
print(b)
output:[4, 6, 9, 4, 7]
2. 浅copy
import copy
a = [3,6,9,4,[7]]
b = copy.copy(a)
a[0] = 4
print(b)
output:[3, 6, 9, 4, [7]]
但是
a[-1].append(9)
print(b)
output:[3, 6, 9, 4, [7, 9]]
并不能完全将二者隔离。
3. 深拷贝
import copy
a = [3,6,9,4,[7]]
b = copy.deepcopy(a)
a[0] = 4
print(b)
a[-1].append(9)
print(b)
output1:[3, 6, 9, 4, [7]]
output2:[3, 6, 9, 4, [7]]
