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HomeBackend DevelopmentPython Tutorialpython复制与引用用法分析

本文实例讲述了python复制与引用用法。分享给大家供大家参考。具体分析如下:

简单复制是引用

a=[1,23,4]
b=a #这是引用
b.append(2323)
print(a,b) #([1, 23, 4, 2323], [1, 23, 4, 2323])

使用copy.copy进行浅拷贝

import copy
c=copy.copy(b)#拷贝
c.append(1)
print(b,c)#([1, 23, 4, 2323], [1, 23, 4, 2323, 1])
list1=[['a'],[1,2,4],[23,'a']]
list_copy=copy.copy(list1)
#浅拷贝,生成了一个新对象,但是新对象内的属性和内容仍然是原对象的引用

#当对新对象进行整体修改的时候修改的是本身
list_copy.append('append')
print(list_copy)#[['a'], [1, 2, 4], [23, 'a'], 'append']
print(list1)#[['a'], [1, 2, 4], [23, 'a']]

#当对新对象的内容进行修改的时候修改的是原对象,因为它仍然是引用
list_copy[1].append('append+')
print(list_copy)#[['a'], [1, 2, 4, 'append+'], [23, 'a'], 'append']
print(list1)#[['a'], [1, 2, 4, 'append+'], [23, 'a']]

使用copy.deepcopy进行迭代拷贝,之后就可以更改新对象的属性而不影响原对象了,只是效率会下降和内存占有量会上升。

对于list,dict,set等可直接使用x(object),object为相应类型,进行拷贝,这是最简单最直接有效地方式。

希望本文所述对大家的Python程序设计有所帮助。

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