python3-- =浅拷贝深拷贝

Posted 2020-12-10 guang2508

1、赋值 =

# alist = [10,20,[100,200]]
# blist = alist
# blist.append(30)
# print(‘alist: ‘,alist,‘ ; id是: ‘,id(alist))
# print(‘blist: ‘,blist,‘ ; id是: ‘,id(blist))
结果：
alist:  [10, 20, [100, 200], 30]  ; id是:  1722968
blist:  [10, 20, [100, 200], 30]  ; id是:  1722968

结论：alist随着blist变化了

 

2、浅拷贝copy.copy()

import copy
alist = [10,20,[100,200]]
blist = copy.copy(alist)#复制
blist.append(30)
print(‘alist: ‘,alist,‘ ; id是: ‘,id(alist))
print(‘blist: ‘,blist,‘ ; id是: ‘,id(blist))
结果：
alist:  [10, 20, [100, 200]]  ; id是:  9734784
blist:  [10, 20, [100, 200], 30]  ; id是:  9734944

import copy
alist = [10,20,[100,200]]
blist = copy.copy(alist)#复制
blist[-1].append(300)
print(‘alist: ‘,alist,‘ ; id是: ‘,id(alist))
print(‘blist: ‘,blist,‘ ; id是: ‘,id(blist))
结果：
alist:  [10, 20, [100, 200, 300]]  ; id是:  7834320
blist:  [10, 20, [100, 200, 300]]  ; id是:  7833640

结论：copy.copy()中， 父级列表完全独立拷贝，全新地址保存，子级列表是共用的，拷贝不彻底 

 

3、深拷贝 copy.deepcopy()

import copy
alist = [10,20,[100,200]]
blist = copy.deepcopy(alist)
blist.append(30)
blist.append(30)
print(‘alist: ‘,alist,‘ ; id是: ‘,id(alist))
print(‘blist: ‘,blist,‘ ; id是: ‘,id(blist))
结果：
alist:  [10, 20, [100, 200]]  ; id是:  16681640
blist:  [10, 20, [100, 200], 30, 30]  ; id是:  16681000

import copy
alist = [10,20,[100,200]]
blist = copy.deepcopy(alist)
# blist.append(30)
blist[-1].append(300)
blist.append(30)
print(‘alist: ‘,alist,‘ ; id是: ‘,id(alist))
print(‘blist: ‘,blist,‘ ; id是: ‘,id(blist))
结果：
alist:  [10, 20, [100, 200]]  ; id是:  13929208
blist:  [10, 20, [100, 200, 300], 30]  ; id是:  13928568

结论：copy.deepcopy()是彻底的拷贝