python复杂代码示例_python复杂对象的复制

# filename : reference.py

animal_list1 = ['cat', 'dog', 'pig', 'fish'];

animal_list2 = animal_list1;

del animal_list1[3]; #delete fish

print 'animal_list1 :', animal_list1;

print 'animal list2 :', animal_list2;

# output is :

# animal_list1 : ['cat', 'dog', 'pig']

# animal list2 : ['cat', 'dog', 'pig']

对象与参考的示例2:

# filename : reference.py

animal_list1 = ['cat', 'dog', 'pig', 'fish'];

animal_list2 = animal_list1[:]; #slice operator

del animal_list1[3]; #delete fish

print 'animal_list1 :', animal_list1;

print 'animal list2 :', animal_list2;

# output is :

# animal_list1 : ['cat', 'dog', 'pig']

# animal list2 : ['cat', 'dog', 'pig', 'fish']

通过上面这两段代码，需要记住的是：

如果只是想用另外一个变量名来操作同一块内存区域，可以如代码1那样操作；否则复杂对象的复制必须使用切片操作来取得拷贝。

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2011-12-06 16:46

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mirguest

2011-12-07

如果更复杂，推荐用copy中的deepcopy进行复制。

Python 2.7.2+ (default, Oct 4 2011, 20:03:08)

[GCC 4.6.1] on linux2

Type "copyright", "credits" or "license()" for more information.

>>> a = range(10)

>>> b = range(11, 20)

>>> a

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>>> b

[11, 12, 13, 14, 15, 16, 17, 18, 19]

>>> c = [a, b]

>>> d = c[:]

>>> d

[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [11, 12, 13, 14, 15, 16, 17, 18, 19]]

>>> d[1][3] = "99"

>>> d

[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [11, 12, 13, '99', 15, 16, 17, 18, 19]]

>>> a

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>>> b

[11, 12, 13, '99', 15, 16, 17, 18, 19]

>>>

>>>

>>> import copy

>>> a = range(10)

>>> b = range(11, 20)

>>> c = [a, b]

>>> d = copy.deepcopy(c)

>>> d

[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [11, 12, 13, 14, 15, 16, 17, 18, 19]]

>>> d[1][3] = "99"

>>> d

[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [11, 12, 13, '99', 15, 16, 17, 18, 19]]

>>> c

[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [11, 12, 13, 14, 15, 16, 17, 18, 19]]

>>> a

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>>> b

[11, 12, 13, 14, 15, 16, 17, 18, 19]

>>>