In this tutorial, we are going to see about Python List.
Python List is one of the most used data structure in Python. Python List is a collection of items in ordered sequence.There are 6 sequences in python and List is one of them.
Python list begins with an opening square bracket and ends with a closing square bracket, [] and you can put multiple data types into a list.
Table of Contents
Let’s learn list with a lot of examples.
Create a list
You can create a list simply using square brackets.
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#Create list with prepopulated elements list1=[1,2,3,4] print("List 1:",list1) #Create an empty list and add elements to it. list2=[] list2.append(1) list2.append(2) list2.append(3) list2.append(4) print("List 2:",list2) |
Output:
Access list elements
You can access list elements with square brackets.Let’s see with the help of example.
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listOfFruits=['Apple','Orange','Banana','Pineapple'] print("First fruit:",listOfFruits[0]) print("Second fruit:",listOfFruits[1]) print("Third fruit:",listOfFruits[2]) print("Fourth fruit:",listOfFruits[3]) |
Output:
Second fruit: Orange
Third fruit: Banana
Fourth fruit: Pineapple
Slicing list
You can use slicing as similar to String in the list.
Use following syntax for slicing.
list1[start:end:step]
All the variables start, end and step are optional.
Start: It denotes starting of the list
Start: It denotes ending of the list
step: It denotes steps for accessing element.
Let’s understand with the help of example.
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listOfFruits=['Apple','Orange','Banana','Pineapple'] #Print first two elements of the list print("First two elements:",listOfFruits[:2]) #Print last two items of the list print("Last two elements:",listOfFruits[2:]) #Print middle elements of the list print("Middle two elements:",listOfFruits[1:3]) #Print elements in step of 2 print("Elements in step 2",listOfFruits[::2]) |
Output:
Please go through above examples and you will be able understand how slicing works.Let’s
You can provide negative indexes also to traverse list in reverse order. -1 is the last index in the list.
Let’s understand with the help of example.
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listOfFruits=['Apple','Orange','Banana','Pineapple'] #Print last three elements of the list print("last three elements:",listOfFruits[-3:]) #Print list in reverse order print("Print list in reverse order:",listOfFruits[::-1]) |
Output:
last three elements: [‘Orange’, ‘Banana’, ‘Pineapple’] Print list in reverse order: [‘Pineapple’, ‘Banana’, ‘Orange’, ‘Apple’]
Python list methods
Please find list of methods which you can use with Python Lists.
| Method | Description |
|---|---|
| append | This method is used to add single item to the end of the list. |
| extend | This method is used to add list of items to the end of the list |
| remove | This method is used to remove element from the list.If element is not present then it will raise error |
| index | This method is used to find index of given element |
| pop | This method will remove and return passed index.If index is not passed then it will remove and return last element from the list. |
| count | This method will count occurences of passed element in the list |
| clear | This method is used to remove all elements of the list. |
| copy | This method is used to shallow copy the list. |
| sort | This method is used to sort the list in ascending or desending order |
| reverse | This method is used to reverse the list. |
| insert | This method is used to add element to the list at specified index. |
Get List’s length
You can use Python’s len function to get length of the list.
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listOfFruits=['Apple','Orange','Banana','Pineapple'] print('Length of listOfFruits is:',len(listOfFruits)) |
Output:
Changing Values in a List with Indexes
You can change value at any index using = operator.
Let’s understand with the help of simple example.
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listOfFruits=['Apple','Orange','Banana','Pineapple'] print("listOfFruits before:",listOfFruits) listOfFruits[1]='Mango' print("listOfFruits after:",listOfFruits) |
Output:
As you can see, value at index 1 of the list changed from ‘Orange’ to ‘Mango’.
List Concatenation and List Replication
You can use + operator to concatenate lists.Please note that it won’t impact original list.If you want to make changes to first list, you need to explicitly assign it.
Let’s understand with the help of simple example.
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list1=['Apple','Orange'] list2=['Banana','Pineapple'] print('ListOfFruits:',list1+list2) |
Output:
You can replicate list with the help of * operator
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list1=['Apple','Orange'] print("List 1:",list1*2) |
Output:
That’s all about Python List.
