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
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
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 :
2001Remove element from a list in Python
Example
list1 = ['mathematic', 'english', 1997, 2000];
print list1
del list1[2];
print "After deleting value at index 2 : "
print list1Output
['mathematic', 'english', 1997, 2000]
After deleting value at index 2 :
['mathematic', 'english', 2000]Basic List Operations
| Python Expression | Results | Description |
| len([1, 2, 3]) | 3 | Length |
| [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] | True | Membership |
| for x in [1, 2, 3]: print x, | 1 2 3 | Iteration |
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 Expression | Results | Description |
| L[2] | SPAM! | Offsets start at zero |
| L[-2] | Spam | Negative: 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. | Function | Description |
| 1 | cmp(list1, list2) | Compares elements of both lists. |
| 2 | len(list) | Gives the total length of the list |
| 3 | max(list) | Returns item from the list with a max value |
| 4 | min(list) | Returns item from the list with min value |
| 5 | list(seq) | Converts a tuple into a list. |
Built-in Python list methods
| Sr.No. | Function | Description |
| 1 | list.append(obj) | Appends object obj to list |
| 2 | list.count(obj) | Returns count of how many times obj occurs in a list |
| 3 | list.extend(seq) | Appends the contents of seq to list |
| 4 | list.index(obj) | Returns the lowest index in a list that obj appears |
| 5 | list.insert(index, obj) | Inserts object obj into a list at offset index |
| 6 | list.pop(obj=list[-1]) | Removes and returns the last object or obj from the list |
| 7 | list.remove(obj) | Removes object obj from the list |
| 8 | list.reverse() | Reverses objects of the list in place |
| 9 | list.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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