What are the basic operations on python lists?

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.

Related free learning recommendations: python tutorial（ Video)

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']

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]

3. Traverse the list

for i in List:
   print i,

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

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 "<pyshell#93>", line 1, in <module>
24     print(a)

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 "<pyshell#104>", line 1, in <module>
18     a.sort()
19 TypeError: unorderable types: str() < int()

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

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

The above is the detailed content of What are the basic operations on python lists?. For more information, please follow other related articles on the PHP Chinese website!