Python List(List)

Sequences are the most basic data structure in Python. Each element in the sequence is assigned a number - its position, or index, the first index is 0, the second index is 1, and so on.

Python has built-in types of 6 sequences, but the most common are lists and tuples.

The sequence can be done by 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.

The

list is the most commonly used Python data type, and it can appear as a comma-separated value in square brackets.

List of data items does not need to have the same type

Create a list by enclosing the different data items separated by commas in square brackets. As shown below:

list1 = ['physics' , 'chemistry', 1997 , 2000] list2 = [< Span class="hl-number">1, 2, 3, 4 , 5 ] list3= [< Span class="hl-quotes">"a", "b" , "c< Span class="hl-quotes">", "d"]

Like the index of a string, the list index starts at 0. The list can be intercepted, combined, and so on.


Access the value in the list

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

Instance (Python 2.0+)

#!/usr/bin/python list1 = [< Span class="hl-quotes">'physics', 'chemistry' , 1997, < Span class="hl-number">2000] list2 = [< Span class="hl-number">1, 2, 3, 4 , 5, < Span class="hl-number">6, 7 ] print "list1[0]: ", list1[0] print "list2[1:5]: ", < Span class="hl-identifier">list2[1:5]

The output of the above example:

list1[0]: physics
List2[1:5]: [2, 3, 4, 5]

Update list

You can modify or update the data items in the list. You can also use the append() method to add list items as follows:

Instance (Python 2.0+)

#!/usr/bin/python # -*- coding: UTF-8 -*- list= [< Span class="hl-brackets">] ## empty list list.append< Span class="hl-brackets">('Google') ## Add elements using append() list.append< Span class="hl-brackets">('WELOOKUPS') print list

Note: We will discuss the use of the append() method in the next section

The output of the above example:

['Google',  'WELOOKUPS']

Delete list elements

You can use the del statement to remove elements of a list, as in the following example:

Instance (Python 2.0+)

#!/usr/bin/python list1 = [< Span class="hl-quotes">'physics', 'chemistry' , 1997, < Span class="hl-number">2000] print list1 del list1[2] print "After deleting value at index 2 : " print list1

The above example output:

['physics', 'chemistry', 1997, 2000]
After deleting value at index 2 :
['physics', 'chemistry', 2000]

note:We will discuss the use of the remove() method in the next section.


Python list script operator

List operators for + and * are similar to strings. The + sign is used for the combined list and the * is used for the repeat list.

As shown below:

Python ExpressionResults Description
len([1, 2, 3])3length
[1, 2, 3] + [4, 5, 6][1, 2, 3, 4, 5, 6] combination< /td>
['Hi!'] * 4['Hi!', 'Hi!', 'Hi!', 'Hi!']Repeat
3 in [1, 2, 3]TrueIs the element present in the list
for x in [1, 2, 3]: print x,1 2 3iteration

Python list interception

Python's list interception example is as follows:

>>>L = ['Google', 'WELOOKUPS', 'Taobao'] >>> L[2] 'Taobao' >>> L[-2] 'WELOOKUPS' >>> L[1:] ['WELOOKUPS', 'Taobao'] >>>





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