{"id":3980,"date":"2020-07-08T16:41:54","date_gmt":"2020-07-08T11:11:54","guid":{"rendered":"https:\/\/www.h2kinfosys.com\/blog\/?p=3980"},"modified":"2020-07-14T16:27:06","modified_gmt":"2020-07-14T10:57:06","slug":"python-list","status":"publish","type":"post","link":"https:\/\/www.h2kinfosys.com\/blog\/python-list\/","title":{"rendered":"Python List:"},"content":{"rendered":"\n

What is List?<\/h2>\n\n\n\n

Let\u2019s think of a list as a cargo train that is used to hold different types of goods for a specific time of period. In python<\/a> lists are just like this train, it is used to store items of the same as well as a different data type.<\/p>\n\n\n\n

\"\"<\/p>\n\n\n\n

We just stored 5 numbers in a list that can be accessed using num_list variable.<\/p>\n\n\n\n

List_of_num = [1,2,3,4,5]\nprint(List_of_num)<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
Different data type elements can also be stored in the list just like the above example. Let\u2019s see<\/p>\n\n\n\n
list_of_num = ['Hello',5,2.99,'World']\nprint(list_of_num)\n<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
Accessing values within lists<\/h2>\n\n\n\n
We can access values stored in the list using the square brackets. Let\u2019s have a look at the example below.<\/p>\n\n\n\n
In the list \u201cHello\u201d is at the 0th index, \u20185\u2019 is at the 1st index, \u20182.99\u2019 is at the 2nd index, \u20185\u2019 is at the 4th index,<\/p>\n\n\n\n
list_of_num = ['Hello',5,2.99,'World']\nprint(list_of_num[0])\nprint(list_of_num[1])\nprint(list_of_num[2])\nprint(list_of_num[3])<\/pre>\n\n\n\n
The shown below will be the output.<\/p>\n\n\n\n
List Comprehension<\/h2>\n\n\n\n
List comprehensions are used for converting one list into another list or creating a new list from other iterables. We can achieve the same task using a simple loop structure<\/a> but list comprehension provides a short syntax to obtain the same results.<\/p>\n\n\n\n
Let\u2019s take an example of finding cubes of a list of numbers. <\/p>\n\n\n\n
Here is an example of using simple loops.<\/p>\n\n\n\n
numbers = [1, 2, 3, 4, 5]\ncubes = []\nfor n in numbers:\n  cubes.append(n**3)\nprint(cubes)<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
Syntax of list comprehension<\/p>\n\n\n\n
new_list = [expression for_loop_one_or_more conditions]<\/pre>\n\n\n\n
Let\u2019s calculate the cubes using list comprehension.<\/p>\n\n\n\n
numbers = [1, 2, 3, 4, 5]\ncubes = [n**3 for n in numbers]\nprint(cubes)<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
Using list comprehension we achieved the same task using in 3 lines instead of 5 lines.<\/p>\n\n\n\n
Append function.<\/h2>\n\n\n\n
Append function is used to add an item at the end of python list just like adding another cabin at the end of the train.\u00a0<\/p>\n\n\n\n
Let\u2019s take a look at the example.<\/p>\n\n\n\n
numbers = [1, 2, 3, 4, 5]\nnumbers.append(6)\nprint(numbers)<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
We can append any type of data.<\/p>\n\n\n\n
numbers = [1, 2, 3, 4, 5]\nnumbers.append(\"six\")\nprint(numbers)<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
Sort function<\/h2>\n\n\n\n
The sort function is used to sort the items in the python list in the ascending as well as descending order.<\/p>\n\n\n\n
numbers = [1, 5, 2, 6, 3, 4]\nnumbers.sort()  # for ascending order\nprint(numbers)\nnumbers.sort(reverse=True)  # for descending order\nprint(numbers)<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
Length function<\/h2>\n\n\n\n
Length function is used to find the length of the list. Let\u2019s take a look at an example to find out the length of the list.<\/p>\n\n\n\n
numbers = [1, 5, 2, 6, 3, 4]\nprint(len(numbers))<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
Reverse function<\/h2>\n\n\n\n
The reverse function is used to reverse the items of the list. Take a look at the example.<\/p>\n\n\n\n
list_of_string = ['I', \"am\", \"here\"]\nlist_of_string.reverse()\nprint(list_of_string)<\/pre>\n\n\n\n
\"\"<\/p>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
What is List? Let\u2019s think of a list as a cargo train that is used to hold different types of goods for a specific time of period. In python lists are just like this train, it is used to store items of the same as well as a different data type. We just stored 5 […]<\/p>\n","protected":false},"author":1,"featured_media":3998,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[342],"tags":[1088,1086,1085,1090,1089,1087],"class_list":["post-3980","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-python-tutorials","tag-append","tag-comprehension","tag-length","tag-python-list","tag-reverse-examples","tag-sort"],"_links":{"self":[{"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/posts\/3980","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/comments?post=3980"}],"version-history":[{"count":0,"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/posts\/3980\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/media\/3998"}],"wp:attachment":[{"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/media?parent=3980"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/categories?post=3980"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.h2kinfosys.com\/blog\/wp-json\/wp\/v2\/tags?post=3980"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}