How to delete element from list python

Best way to remove elements from a list

I would like to know what is the best way/efficient way to remove element(s) from the list.

There are few functions provided by Python:

4 Answers 4

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My answer is not exactly to your question but after you read this, I hope you can decide which type you need to choose for your needs.

Python’s lists are variable-length arrays, not Lisp-style linked lists. The implementation uses a contiguous array of references to other objects, and keeps a pointer to this array.

This makes indexing a list a[i] an operation whose cost is independent of the size of the list or the value of the index.

When items are appended or inserted, the array of references is resized. Some algorithm is applied to improve the performance of appending items repeatedly; when the array must be grown, some extra space is allocated so the next few times don’t require an actual resize i.e over-allocation. More Information

Removing vs Pop vs Delete:

At first glance it looks like all of them are doing the same thing.

Under the hood its behaving different.

removing : remove an element from the list by iterating from 0 index till the first match of the element is found. taking more time to iterate if the element is at the end.

pop : removing element from the list by using the index. taking less time.

del : is a python statement that removes a name from a namespace, or an item from a dictionary, or an item from a list by using the index.

Benchmark:

Worst case : deleting from the end of the list.

Best case: begining of the list.

Point to be noted:

if array grows or shrinks in the middle

So, now I hope you can decide what you need to choose for your needs.

How to remove elements from a list in Python?

In this article, we will go through all the methods to remove elements from a list in Python.

Python lists are the most basic data structure used in day-to-day programming. We come across situations where we need to remove elements from lists and in this article, we’ll discuss exactly that.

1. Remove Elements From a List Based on the Values

One of the reasons Python is a renowned programming language is the presence of the numerous inbuilt functions. These inbuilt functions are very handy and thereby make Python very convenient to write.

remove() function

Python has an inbuilt function, remove() that helps us to remove elements based on the value.

OUTPUT:

The key things to note here are:

Error-free usage of remove() function

There is an easy way to bypass the error while removing an element in case the programmer is unaware of its presence on the list. We’ll do this using the if condition.

OUTPUT:

In the above code snippet, we first check the presence of the value in the list before removing.

Remove all the occurrences of a value in a list

As we previously mentioned, remove() function only removes the first occurrence of a value. In order to take out all the instances of said value, we will do use the while loop.

OUTPUT:

This sums up the usage of remove() function.

2. Removing elements based on an index

There can be a few ways to remove elements based on the index. Let us quickly go through each one of them.

del keyword

del is a powerful tool in Python which is used to remove entire objects. It can also be used to remove elements from a given list.

OUTPUT:

Some of the observations derived from the above script are:

pop() function

As the name suggests, pop() function pops out an element from a specified index.

OUTPUT:

What we learnt about pop() method here is:

We have a complete article on the use of pop() method.

3. Removing a range of elements from a list

Python has a provision of removing a range of elements from a list. This can be done by del statement.

OUTPUT:

Let us try to understand the process:

4. Remove all the elements from the list

Python provides a method to empty the entire list in a single line.

OUTPUT:

If the function applied to an empty list, it does not raise any error.

Conclusion

It is up to your discretion to use the way of removing elements from a list, either by value or index. Different circumstances require a different approach, therefore Python provides various methods of removing elements from a Python list.

We hope the reader had no difficulty in following the article. Feel free to comment below for any queries related to the subject.

How to remove an element from a list by index

How do I remove an element from a list by index?

19 Answers 19

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Use del and specify the index of the element you want to delete:

Also supports slices:

Here is the section from the tutorial.

You probably want pop :

By default, pop without any arguments removes the last item:

Like others mentioned pop and del are the efficient ways to remove an item of given index. Yet just for the sake of completion (since the same thing can be done via many ways in Python):

Using slices (this does not do in place removal of item from original list):

(Also this will be the least efficient method when working with Python list, but this could be useful (but not efficient, I reiterate) when working with user defined objects that do not support pop, yet do define a __getitem__ ):

This makes this method very inefficient and it can also produce undesirable side effects (especially when other variables point to the original list object which remains un-modified).

This Stack Overflow answer explains the concept of slicing.

Also note that this works only with positive indices.

While using with objects, the __getitem__ method must have been defined and more importantly the __add__ method must have been defined to return an object containing items from both the operands.

In essence, this works with any object whose class definition is like:

This works with list which defines __getitem__ and __add__ methods.

Comparison of the three ways in terms of efficiency:

Assume the following is predefined:

The del object[index] method:

By far the most efficient method. It works will all objects that define a __del__ method.

The disassembly is as follows:

pop method:

It is less efficient than the del method and is used when you need to get the deleted item.

The slice and add method.

The least efficient.

Python : How to remove element from a list by value or Index | remove() vs pop() vs del

In this article we will discuss different ways to remove an elements from list.

Remove an element from List by value using list.remove()

Python’s list provides a member function to remove an element from list i.e.

It removes the first occurrence of given element from the list.

Suppose we have a list of numbers i.e.

Let’s remove 56 from the given list using list.remove() i.e.

It will remove the first occurrence of 56 from the above lists. Lists contents will be now,

If we try to remove the element that doesn’t exists in list then list.remove() will throw exception.
Therefore before calling list.remove() we should either,

Check if element exists in list i.e.

Or use try / except i.e.

Related Articles

Remove an element from List by Index using list.pop()

In python list’s pop() function will remove the element at given index and also returns the deleted element.
If index is not given then it deletes the last element.

We have a list of ints i.e.

Let’s remove element at index 2

List’s contents will be now

Returned value is 12 i.e. the deleted element.

list.pop() and Runtime Error

If list.pop() is called an index that is out of the boundary of List then it will generate a runtime error.
Therefore we should always check the size of list before calling list.pop() i.e.

or Use try / except

Remove an element from List by del

In python del is a keyword and can be used to delete the element in list by index i.e.

It will delete the element at index 2 in list.

If del list[index] is called on an index that is out of the boundary of List then it will generate a runtime error.
Therefore check size of list before calling del i.e.

or Use try / except

Complete example is as follows,

Output:

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Remove element from a Python LIST [clear, pop, remove, del]

Updated July 9, 2022

Python List data-type helps you to store items of different data types in an ordered sequence. The data is written inside square brackets ([]), and the values are separated by comma(,).

Besides the list methods, you can also use a del keyword to remove items from a list.

In this Python tutorial, you will learn:

Example of list

The index starts from 0. In the list: my_list at

0 th index we have the string ‘Guru’,

Python remove() method

Python removes () method is a built-in method available with the list. It helps to remove the given very first element matching from the list.

Syntax:

The element that you want to remove from the list.

ReturnValue

There is no return value for this method.

Tips for using remove() method:

Following are the important points to remember when using remove () method:

Example: Using remove() method to remove an element from the list

Here is a sample list that i have

The list has elements of date-types string and number. The list has duplicate elements like number 12 and string Riya.

Python pop() method

The pop() method removes an element from the list based on the index given.

Syntax

index: the pop() method has only one argument called index.

ReturnValue:

The pop() method will return the element removed based on the index given. The final list is also updated and will not have the element.

Example: Using the pop() method to remove an element from the list

Let us try to remove element using a pop() method based on the following :

Python clear() method

The clear() method will remove all the elements present in the list.

Syntax:

Ther is no return value. The list() is emptied using clear() method.

Example: Using clear() method to remove all elements from the list

The clear() method will empty the given list. Let us see the working of clear() in the example below:

Using del keyword

To remove an element from the list, you can use the del keyword followed by a list. You have to pass the index of the element to the list. The index starts at 0.

Syntax:

You can also slice a range of elements from the list using the del keyword. The start/stop index from the list can be given to del keyword, and the elements falling in that range will be removed. The syntax is as follows:

Syntax:

Here is an example that shows to remove the first element, last element, multiple elements from the list using del.

How do I remove the first element from a list?

You can make use of list methods like remove(), pop() to remove the first element from the list. In the case of remove() method, you will have to pass the first element to be removed and for pop the index, i.e., 0.

You may also use the del keyword to remove the first element from the list.

The example below shows to remove first element from list using remove(), pop() and del.

How do I remove multiple elements from a list in Python?

The list methods remove(), and pop() are meant to remove a single element. To remove multiple aspects, make use of the del keyword.

From the list [‘A’, ‘B’, ‘C’, ‘D’, ‘E’, ‘F’], we want to remove elements B, C and D. Below example shows the how to make use of del keyword to remove the elements.

How do I remove an element from a list by using index in Python?

Summary:

In Python, there are many methods available on the list data type that helps you to remove an element from a given list. The methods are remove(), pop() and clear().

Important built-in methods available on list to remove elements