python中的深copy和淺copy

bytes

Python bytes/str
bytes 在Python3中作為一種單獨的數據類型，不能拼接，不能拼接，不能拼接

>>> '€20'.encode('utf-8')
b'\xe2\x82\xac20'
>>> b'\xe2\x82\xac20'.decode('utf-8')
'€20'

解碼

>>> b'\xa420'.decode('windows-1255')
'₪20'

深copy和淺copy
深copy新建一個對象重新分配內存地址，復制對象內容。淺copy不重新分配內存地址，內容指向之前的內存地址。淺copy如果對象中有引用其他的對象，如果對這個子對象進行修改，子對象的內容就會發生更改。

import copy

#這里有子對象
numbers=['1','2','3',['4','5']]
#淺copy
num1=copy.copy(numbers)
#深copy
num2=copy.deepcopy(numbers)

#直接對對象內容進行修改
num1.append('6')

#這里可以看到內容地址發生了偏移，增加了偏移‘6’的地址
print('numbers:',numbers)
print('numbers memory address:',id(numbers))
print('numbers[3] memory address',id(numbers[3]))
print('num1:',num1)
print('num1 memory address:',id(num1))
print('num1[3] memory address',id(num1[3]))


num1[3].append('6')

print('numbers:',numbers)
print('num1:',num1)
print('num2',num2)

輸出：
numbers: ['1', '2', '3', ['4', '5']]
numbers memory address: 1556526434888
numbers memory address 1556526434952
num1: ['1', '2', '3', ['4', '5'], '6']
num1 memory address: 1556526454728
num1[3] memory address 1556526434952
numbers: ['1', '2', '3', ['4', '5', '6']]
num1: ['1', '2', '3', ['4', '5', '6'], '6']
num2 ['1', '2', '3', ['4', '5']]