Python Lists Methods

In this lesson, we’ll discuss Python lists methods with examples in order to achieve our instructional goals.

Lists/Array Methods In Python

There are several built-in Python lists methods that you can use when dealing with Python lists or Array.

Here, you will discover the entire assortment of methods for working with Python lists/arrays, complete with examples.

Python List append() Method

In Python list, the append() method is apply to declare an item at the end of the list.

Syntax:

list.append(elmnt)

Parameter Values

A new item should be added to the companies list:

To incorporate a new list of companies to an existing one, simply append the new list to the current one:

Python List clear() Method

The clear() method in Python eliminates all of the items from a list.

Syntax

list.clear()

Clear all items from the firms list.

Now attempt to combine 2 lists and then delete all items from the list:

As demonstrated in the example above, the first print will feature the list item, while the second print will show an empty list.

Python List copy() Method

The copy() method in Python returns a replica of the designated list.

Syntax:

list.copy()

Duplicate the firms list:

Now duplicate both old firms and newfirms list items in a single list:

Python Lists Methods: count()

The python count() method furnishes the amount of elements with a designated value.

Syntax:

list.count(value)

Parameter Values

Determine how many times the name “Google” appears in the list of firms:

Here is another example:

Python Lists Methods: extend()

The extend() method of python appends the certain list items (or any iterable) to the end of the existing list.

Syntax:

list.extend(iterable)

Parameter Values

Place the companies’ items in the newfirms list:

Now add three list items in a single list:

Python Lists Methods: index()

When the index() method is called, it returns the position where the given value first occurs.

Syntax:

list.index(elmnt)

You will only get the first occurrence of the value with the index() method.

Combine the two lists/arrays and find the position of “Alphabet Inc”:

Python Lists Methods: insert()

When insert() is called, the given value is inserted at the chosen position.

Syntax:

list.insert(pos, elmnt)

Parameter Values

In the firms list, add “wallmart” as the fift element:

The next step is to add the value “IBM” at the end of the list of firms and extend it with newfirms list:

Python Lists Methods: pop()

Using pop(), you can remove an element from a particular position.

Syntax:

list.pop(pos)

Parameter Values

From the frms list, remove the fourth element:

The removed element should be returned from the firms list/array as follows:

Python Lists Methods: remove()

When Python remove() method is called, it removes the first occurrence of the element with the specified value.

Syntax:

list.remove(elmnt)

Parameter Values

Remove the “Meta” element of the firms list:

Take both lists/arrays and merge them. Remove the last element from the merged list:

Python Lists Methods: reverse()

With Python’s reverse() method, the elements are sorted in reverse order.

Syntax:

list.reverse()

List the firms in reverse order:

Then, merge the two Python lists/arrays and print them in reverse order:

Python Lists Methods: sort()

Lists are sorted ascending by default with the sort() method.

If you want to decide what sorting criteria should be used, you can also write a function.

Syntax:

list.sort(reverse=True|False, key=myFunc)

Parameter Values

The firms list should be sorted alphabetically as follows:

List the firms in descending order:

The list of firms should now be sorted by their length:

Note that by default length, lists elements are displayed from smaller to bigger characters.

Now sort the firms list by their characters’ length in reverse order:

The firms’ lists/arrays should now be merged and sorted by the length of their characters in default order:

Python Lists Methods Importance

Here are some key reasons highlighting the importance of Python list methods:

1. List methods such as append(), extend(), insert(), remove(), and pop() allow for dynamic modification of list contents. These methods enable you to add elements to the list, remove specific elements, insert elements at specific positions, and retrieve and remove elements from the list based on their indices. These operations are fundamental for maintaining and updating list data.
2.  List methods like index() and count() provide convenient ways to search for elements within a list. The index() method returns the index of the first occurrence of a specified element, enabling quick access to the desired data. The count() method counts the number of occurrences of a given element within the list, aiding in data analysis and statistics.
3. The sort() method allows you to sort the elements of a list in-place, either in ascending or descending order. Sorting lists is crucial for various applications, including data organization, efficient search, and algorithmic implementations. Additionally, the reverse() method reverses the order of elements in a list, providing a quick way to change the sequence of data.
4. The copy() method creates a shallow copy of a list, allowing you to create an independent copy of the original list. This is important when you need to modify one list while preserving the integrity of the other. The copy() method prevents unintended side effects that can occur when multiple variables refer to the same list object.
5. List slicing, facilitated by the use of indexing and slicing notation, allows you to extract specific portions of a list. Slicing is useful for operations such as extracting subsets of data, manipulating specific ranges of elements, or creating new lists based on certain criteria. It provides a flexible and efficient way to work with different parts of a list.