Python之List列表如何处理最好？正确案例详解(3)

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Python之List列表如何处理最好？正确案例详解(3)

0] = [7, 8, 9] # 第一层修改不会改变被复制对象 >>> a, b ([[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [4, 5, 6]]) >>> b[0][0] = 100 # 第二层修改会改变被复制对象 >>> a, b ([[1, 2, 3], [100, 5, 6]], [[7, 8, 9], [100, 5, 6]]

多维深层复制，完全不会改变被复制对象

>>> a = [[1,2,3], [4, 5,6]]
>>> b = deepcopy(a)
>>> b[0] = [7, 8, 9]
>>> b[1][0] = 100
>>> a, b
([[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [100, 5, 6]])

增加列表内容

插入

>>> a = [1, 2, 3, 4]
>>> a.insert(0, 0)
[0, 1, 2, 3, 4]
>>> a.insert(2, 12)
[0, 1, 12, 2, 3, 4]
>>> a.insert(100, 99)
[0, 1 ,12, 2, 3, 4, 99]

插入多列

>>> a[2:2] = [20, 21, 22]
[0, 1, 20, 21, 22, 12, 2, 3, 4, 99]

后面附上

>>> a = [0]
>>> a = a.append(1)
>>> a = a.append(2)
[0, 1, 2]

重复内容

>>> a = [1,2] * 5
[1, 2, 1, 2, 1, 2, 1, 2, 1, 2]

列表组合

>>> a, b = [1, 2], [3, 4]
>>> a + b
[1, 2, 3, 4]
>>> c = a.extend(b)
>>> a, c
([1, 2, 3, 4], None)

删除列表内容

以索引来删除

>>> a = [1, 2, 3, 4, 3]
>>> b = a.pop(0)
>>> a, b
([2, 3, 4, 3], 1)

以值来删除第一个

>>> a.remove(3)
[2, 4, 3]

直接删除

>>> del a[1:]
[2]

列表的其他方法

计数该值出现的次数

>>> a = [1, 3, 3, 5, 3, 2, 6, 3]
>>> a.count(3)
4

返回该值的第一個索引

>>> a.index(5)
3

列表排序，不修改

>>> c = sorted(a)
>>> a, c
([1, 3, 3, 5, 3, 2, 6, 3], [1, 2, 3, 3, 3, 3, 5, 6])

列表排序，自修改

>>> c = a.sort()
>>> a, c
([1, 2, 3, 3, 3, 3, 5, 6], None)

倒序

>>> a = [1, 2, 3, 4]
>>> a[::-1]
[4, 3, 2, 1]
>>> c = a.reverse()
>>> a, c
([4, 3, 2, 1], None)

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