What are the basic operations on python lists?-Python Tutorial-php.cn

The basic operations of python lists are: 1. Create a list, just enclose different data items separated by commas in square brackets; 2. Add new elements; 3. Traverse the list; 4. Access the list The value; 5. Delete elements from the list.

What are the basic operations on python lists?

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The basic operations of python lists are:

Mainly introduces the detailed operation methods of lists (List) in Python, including creating, For access, update, delete, other operations, etc., friends in need can refer to it.

1. Create a list.Just enclose the different data items separated by commas in square brackets

List = ['wade','james','bosh','haslem']

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Like the index of the string, the list index starts from 0. The list can be intercepted, combined, etc.

2. Add new elements

1 List.append('allen') #方式一：向list结尾添加 参数object 2 >>> a=[1,2,3,4] 3 >>> a.append(5) 4 >>> print(a) 5 [1, 2, 3, 4, 5] 6 7 List.insert(4,'lewis') #方式二：插入一个元素 参数一：index位置 参数二：object 8 >>> a=[1,2,4] 9 >>> a.insert(2,3) 10 >>> print(a) 11 [1, 2, 3, 4] 12 13 List.extend(tableList) #方式三：扩展列表，参数：iterable参数 14 >>> a=[1,2,3] 15 >>> b=[4,5,6] 16 >>> a.extend(b) 17 >>> print(a) 18 [1, 2, 3, 4, 5, 6]

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3. Traverse the list

for i in List: print i,

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4. Access the values in the list

Use subscript index to access the values in the list. You can also use square brackets to intercept characters, as shown below:

>>> List = [1, 2, 3, 4, 5, 6, 7 ] >>> print(List[3]) 4

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5. Delete elements from list

1 List.remove() #删除方式一：参数object 如有重复元素，只会删除最靠前的 2 >>> a=[1,2,3] 3 >>> a.remove(2) 4 >>> print(a) 5 [1, 3] 6 7 List.pop() #删除方式二：pop 可选参数index删除指定位置的元素 默认为最后一个元素 8 >>> a=[1, 2, 3, 4, 5, 6] 9 >>> a.pop() 10 6 11 >>> print(a) 12 [1, 2, 3, 4, 5] 13 14 15 del List #删除方式三：可以删除整个列表或指定元素或者列表切片，list删除后无法访问。 16 >>> a=[1, 2, 3, 4, 5, 6] 17 >>> del a[5] 18 >>> print(a) 19 [1, 2, 3, 4, 5] 20 >>> del a 21 >>> print(a) 22 Traceback (most recent call last): 23 File "", line 1, in  24 print(a)

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6. Sort and reverse code

1 List.reverse() 2 >>> a=[1, 2, 3, 4, 5, 6] 3 >>> a.reverse() 4 >>> print(a) 5 [6, 5, 4, 3, 2, 1] 6 7 8 List.sort() #sort有三个默认参数 cmp=None,key=None,reverse=False 因此可以制定排序参数 9 >>> a=[2,4,6,7,3,1,5] 10 >>> a.sort() 11 >>> print(a) 12 [1, 2, 3, 4, 5, 6, 7] 13 #python3X中，不能将数字和字符一起排序，会出现此报错 14 >>> a=[2,4,6,7,3,1,5,'a'] 15 >>> a.sort() 16 Traceback (most recent call last): 17 File "", line 1, in  18 a.sort() 19 TypeError: unorderable types: str() < int()

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7. Python list interception

Python’s list interception has the same type as string operation, as shown below:

L = ['spam', 'Spam', 'SPAM!'] 操作： Python 表达式 结果 描述 L[2] 'SPAM!' 读取列表中第三个元素 L[-2] 'Spam' 读取列表中倒数第二个元素 L[1:] ['Spam', 'SPAM!'] 从第二个元素开始截取列表

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8. Python list operation functions and methods

List operations include the following functions:

1. cmp(list1, list2): compare elements of two lists (python3 has been discarded)

2. len(list): list Number of elements

3. max(list): Returns the maximum value of list elements

4. min(list): Returns the minimum value of list elements

5. list(seq ): Convert tuple to list

1 列表操作常用操作包含以下方法: 2 1、list.append(obj)：在列表末尾添加新的对象 3 2、list.count(obj)：统计某个元素在列表中出现的次数 4 3、list.extend(seq)：在列表末尾一次性追加另一个序列中的多个值（用新列表扩展原来的列表） 5 4、list.index(obj)：从列表中找出某个值第一个匹配项的索引位置 6 5、list.insert(index, obj)：将对象插入列表 7 6、list.pop(obj=list[-1])：移除列表中的一个元素（默认最后一个元素），并且返回该元素的值 8 7、list.remove(obj)：移除列表中某个值的第一个匹配项 9 8、list.reverse()：反向列表中元素 10 9、list.sort([func])：对原列表进行排序

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