Sequence is the most basic data structure in Python. Each element in the sequence is assigned a number - its position, or index, with the first index being 0, the second index being 1, and so on.
Python has 6 built-in types for sequences, but the most common are lists and tuples.
Operations that can be performed on sequences include indexing, slicing, adding, multiplying, and checking members.
In addition, Python has built-in methods for determining the length of a sequence and determining the largest and smallest elements.
List is the most commonly used Python data type, which can appear as a comma-separated value within square brackets.
The data items of the list do not need to be of the same type
To create a list, just use square brackets to enclose the different data items separated by commas. It looks like this:
list1 = ['physics', 'chemistry', 1997, 2000] list2 = [1, 2, 3, 4, 5 ] list3 = ["a", "b", "c", "d"]
Like string indexing, list indexing starts at 0. Lists can be intercepted, combined, etc.
Access the values in the list:
Use the subscript index to access the values in the list. You can also use square brackets to intercept characters, as shown below:
#!/usr/bin/python list1 = ['physics', 'chemistry', 1997, 2000] list2 = [1, 2, 3, 4, 5, 6, 7 ] print "list1[0]: ", list1[0] print "list2[1:5]: ", list2[1:5]
The above example output results:
list1[0]: physics list2[1:5]: [2, 3, 4, 5]
Update list
You can modify or update the data items in the list, or you can use the append() method to add List items, as shown below:
#!/usr/bin/python # -*- coding: UTF-8 -*- list = [] ## 空列表 list.append('Google') ## 使用 append() 添加元素 list.append('Runoob') print list
Output results of the above example:
['Google', 'Runoob']
Delete list elements
You can use the del statement to delete elements of the list, as shown in the following example :
#!/usr/bin/python list1 = ['physics', 'chemistry', 1997, 2000] print list1 del list1[2] print "After deleting value at index 2 : " print list1
Output results of the above examples:
['physics', 'chemistry', 1997, 2000] After deleting value at index 2 : ['physics', 'chemistry', 2000]
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