Lists in Python

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09 Mar 2023
Intermediate
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Introduction

Understanding the power of Python lists can give you an incredible advantage when coding. List manipulation is an essential skill for all coders, and it's a good place to start your programming journey especially if you're interested in data science. In this article, we'll take a deep dive into everything you need to know about Python lists. We'll discuss how they work, their various methods and functions, and some useful tips so that you can use them effectively in your own projects! Now let's jump right in!

What is a List in Python?

A python list is a powerful tool for data management in python language programming. It is one of the most commonly used data structures that can store information sequentially in an organized manner. Python lists are incredibly versatile and allow for the quick execution of python list operations. These can range from simple addition or removal of elements, sorting the elements according to specified criteria, looping through the python list and performing certain actions on it, and more advanced list comprehension techniques to transform data into usable forms. In python programming, python lists are invaluable in storing and manipulating data quickly and efficiently.

Example

list1 = ['mathematic', 'english', 1997, 2000];
list2 = [1, 2, 3, 4, 5 ]
list3 = ["a", "b", "c", "d"]

Accessing list elements in python

accessing list elements in python requires understanding how to use Python's indexes. With indexing, the developer can access each element of a list quickly and easily by specifying its position in the list. This can be done using integers or negative numbers. Integers start from 0 and move up to the length of the list minus one, while negative numbers start from -1 and move down to -len(list). Knowing this, accessing individual values or even slices of a list becomes a breeze by accessing the right index or range of indexes. Using accessing list elements in Python enables greater control over data manipulation within the code.

Example

list1 = ['mathematic', 'chemistry', 1997, 2000];
list2 = [1, 2, 3, 4, 5, 6, 7 ];
print "list1[0]: ", list1[0]
print "list2[1:5]: ", list2[1:5]

Output

list1[0]: mathematic
list2[1:5]: [2, 3, 4, 5]

Update List in Python 

Updating a list in python is an essential part of developing programs and applications. List updates allow the programmer to easily move, alter, and modify data that is stored in the list such as strings and values. This process helps make programming more time-efficient and can simplify coding tasks. List updates are closely related to array-based operations, but provide an even greater level of control over the representation and use of any given list. Keeping lists updated ensures that python code runs optimally without disruption or errors. List update syntax within Python language offers a great way for developers to customize their applications for each individual use case; making python one of the most powerful programming languages available today.

Example

list = ['mathematic', 'chemistry', 1997, 2000];
print "Value available at index 2 : "
print list[2]
list[2] = 2001;
print "New value available at index 2 : "
print list[2]

Output

Value available at index 2 :
1997
New value available at index 2 :
2001

Remove element from a list in Python

Delete List Elements in Python is easy to do. By using the del() method or the pop() method the developer can eliminate values from a given list. The del() method will allow the user to completely remove an element from a list, while pop() allows its users to temporarily delete an element and store its value in another variable if desired. When using either of these methods it is important to consider their indexing system, which starts at 0, so depending on how many elements a list has will affect the indexes available. Delete List Elements in Python gives the convenience of having complete control over what elements are still part of a list, when changes need to be made it can be done quickly and without complication.

Example

list1 = ['mathematic', 'english', 1997, 2000];
print list1
del list1[2];
print "After deleting value at index 2 : "
print list1

Output

['mathematic', 'english', 1997, 2000]
After deleting value at index 2 :
['mathematic', 'english', 2000]

Basic List Operations

Working with basic lists in Python is a great way to start introducing more advanced coding concepts. It allows the developer to manipulate data and create basic structures that are essential for solving programming challenges. Basic list operations in python include performing basic arithmetic on the numbers contained within a list, accessing elements of an existing list, replacing elements of a list, rearranging elements of a list, concatenating multiple lists together, and duplicating specific entries in a list.
Python ExpressionResultsDescription
len([1, 2, 3])3Length
[1, 2, 3] + [4, 5, 6][1, 2, 3, 4, 5, 6]Concatenation
['Hi!'] * 4['Hi!', 'Hi!', 'Hi!', 'Hi!']Repetition
3 in [1, 2, 3]TrueMembership
for x in [1, 2, 3]: print x,1 2 3Iteration

Indexing, Slicing, and Matrixes in python

Indexing, slicing, and matrixes are integral parts of understanding Python. The index function in Python is used to locate a certain item in a string, list, or other data types. It finds the index by searching for the location of the item within its respective data set. Meanwhile, the slice operator in python is used to create subsets from larger strings and lists by indexing characters at certain locations. Lastly, python matrixes are special groups of elements that use index functions to find items inside them; they are typically used for manipulating numerical data. Together, understanding indexing, slicing, and matrixes in Python can help anyone more efficiently perform complex tasks such as searching for specific database items and running elaborate calculations.

Python ExpressionResultsDescription
L[2]SPAM!Offsets start at zero
L[-2]SpamNegative: count from the right
L[1:]['Spam', 'SPAM!']Slicing fetches sections

Python inbuilt functions

Python inbuilt functions can be a great tool for a variety of different tasks. These native features of python provide developers with many opportunities to create useful and efficient code. From basic string manipulations to complex number crunching, python offers powerful commands at our disposal. Highlighting their simplicity and brevity, python inbuilt functions serve as succinct replacements for longer programming codes that perform the same task. Whether anyone is new to python or an experienced user, python inbuilt functions are always worthwhile knowing and utilizing in that particular codebase.

Sr.No.FunctionDescription
1cmp(list1, list2)Compares elements of both lists.
2len(list)Gives the total length of the list
3max(list)Returns item from the list with a max value
4min(list)Returns item from the list with min value
5list(seq)Converts a tuple into a list.

Built-in Python list methods

Sr.No.FunctionDescription
1list.append(obj)Appends object obj to list
2list.count(obj)Returns count of how many times obj occurs in a list
3list.extend(seq)Appends the contents of seq to list
4list.index(obj)Returns the lowest index in a list that obj appears
5list.insert(index, obj)Inserts object obj into a list at offset index
6list.pop(obj=list[-1])Removes and returns the last object or obj from the list
7list.remove(obj)Removes object obj from the list
8list.reverse()Reverses objects of the list in place
9list.sort([func])Sorts objects of the list, use compare func if given
Summary

Python lists offer tremendous flexibility and make organizing data a breeze. With the vast range of methods available for manipulating, adding, and deleting list elements, any coding task can become vastly simplified. Now that we have gone through the basics of Python Lists, it should be much easier to build applications or APIs that are powered by lists. So don’t hesitate, you’ll be amazed at how much easier your programming tasks become when you master this essential skill in the Python language.

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