How to remove element from list python

In this article, you’ll learn how to use Python’s built-in remove() list method.

By the end, you’ll know how to use remove() to remove an item from a list in Python.

Here is what we will cover:

The remove() method is one of the ways you can remove elements from a list in Python.

The remove() method removes an item from a list by its value and not by its index number.

The general syntax of the remove() method looks like this:

Let’s break it down:

If you need to remove an item by its index number and/or for some reason you want to return (save) the value you removed, use the pop() method instead.

How to Remove an Element from a List Using the remove() Method in Python

To remove an element from a list using the remove() method, specify the value of that element and pass it as an argument to the method.

remove() will search the list to find it and remove it.

If you specify a value that is not contained in the list, then you’ll get an error – specifically the error will be a ValueError :

To avoid this error from happening, you could first check to see if the value you want to remove is in the list to begin with, using the in keyword.

It will return a Boolean value – True if the item is in the list or False if the value is not in the list.

Another way to avoid this error is to create a condition that essentially says, «If this value is part of the list then delete it. If it doesn’t exist, then show a message that says it is not contained in the list».

Now, instead of getting a Python error when you’re trying to delete a certain value that doesn’t exist, you get a message returned, saying the item you wanted to delete is not in the list you’re working with.

The remove() Method Removes the First Occurrence of an Item in a List

A thing to keep in mind when using the remove() method is that it will search for and will remove only the first instance of an item.

This means that if in the list there is more than one instance of the item whose value you have passed as an argument to the method, then only the first occurrence will be removed.

Let’s look at the following example:

In the example above, the item with the value of Python appeared three times in the list.

When remove() was used, only the first matching instance was removed – the one following the JavaScript value and preceeding the Java value.

The other two occurrences of Python remain in the list.

What happens though when you want to remove all occurrences of an item?

Using remove() alone does not accomplish that, and you may not want to just remove the first instance of the item you specified.

How to Remove All Instances of an Item in A List in Python

One of the ways to remove all occurrences of an item inside a list is to use list comprehension.

List comprehension creates a new list from an existing list, or creates what is called a sublist.

This will not modify your original list, but will instead create a new one that satisfies a condition you set.

In the example above, there is the orginal programming_languages list.

Then, a new list (or sublist) is returned.

Now, if you don’t want to create a new list, but instead want to modify the already existing list in-place, then use the slice assignment combined with list comprehension.

With the slice assignment, you can modify and replace certain parts (or slices) of a list.

To replace the whole list, use the [:] slicing syntax, along with list comprehension.

The list comprehension sets the condition that any item with a value of Python will no longer be a part of the list.

Conclusion

And there you have it! You now know how to remove a list item in Python using the remove() method. You also saw some ways of removing all occurrences of an item in a list in Python.

I hope you found this article useful.

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how to safely remove elements from a list in Python

I loop through a list and remove the elements that satisfy my condition. But why doesn’t this work, as noted below? Thank you.

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You cannot change something while you’re iterating it. The results are weird and counter-intuitive, and nearly never what you want. In fact, many collections explicitly disallow this (e.g. sets and dicts).

Why don’t you just do this initially in the list comprehension? E.g.

You can also use this to construct a new list from the existing list, e.g.

The idea of filtering is a good one, however it misses the point which is that some lists may be very large and the number of elements to remove may be very small.

In which case the answer is to remember the list indexes of the elements to remove and then iterate through the list of indexes, sorted from largest to smallest, removing the elements.

which makes sense if you step through it like so:

The only real solution is do not change the number of items in the list while you are iterating over it. Copy the items you want to keep to a new list, or keep track of the values you want to remove and do the remove-by-value in a separate pass.

How to Remove an Item from Python List?

Python – Remove an Item from List

To remove an item from Python List, you can use remove() method on the list with the item passed as argument.

In this tutorial, we shall go through examples, to understand how to use remove() function, to delete an item from the list.

Syntax – remove()

The syntax of remove() method is:

where thisitem has to be removed from mylist.

The remove() method removes only the first occurrence of the item in the list. The subsequent occurrences are untouched. At the end of this article, we will also learn to remove all of those items with a specific value.

Example 1: Remove item that is present only once in the List

In the following example, we have a list with multiple items. And the item we would like to remove, 5, is present only once.

Python Program

Output

The item is removed and the index of subsequent items is reduced by 1.

Example 2: Remove item that is present multiple times in the List

In the following example, we have a list with multiple items. And the item we would like to remove, 21, is present twice.

Python Prgoram

Output

The item is present twice, but only the first occurrence is removed.

Example 3: Remove all the occurrences of an item from the List

In this example, we will remove all the elements that match a specific value, 21.

Python Program

Output

Summary

In this tutorial of Python Examples, we learned how to remove an item from the list, could be first occurrence or all occurences.

How to delete an item in a list if it exists?

I am getting new_tag from a form text field with self.response.get(«new_tag») and selected_tags from checkbox fields with

I combine them like this:

( f1.striplist is a function that strips white spaces inside the strings in the list.)

For example, from logging.info :

How do I get rid of the empty string?

If there is an empty string in the list:

But if there is no empty string:

Why does this happen, and how do I work around it?

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1) Almost-English style:

Test for presence using the in operator, then apply the remove method.

2) Duck-typed, EAFP style:

This shoot-first-ask-questions-last attitude is common in Python. Instead of testing in advance if the object is suitable, just carry out the operation and catch relevant Exceptions:

Off course the second except clause in the example above is not only of questionable humor but totally unnecessary (the point was to illustrate duck-typing for people not familiar with the concept).

If you expect multiple occurrences of thing:

However, with contextlib’s suppress() contextmanager (introduced in python 3.4) the above code can be simplified to this:

Again, if you expect multiple occurrences of thing:

3) Functional style:

4) Mathematical style:

List comprehensions became the preferred style for list manipulation in Python since introduced in version 2.0 by PEP 202. The rationale behind it is that List comprehensions provide a more concise way to create lists in situations where map() and filter() and/or nested loops would currently be used.

Python remove element from list [Practical Examples]

Table of Contents

Introduction to Python remove element from list

A list is an ordered and mutable Python container, being one of the most common data structures in Python. To create a list, the elements are placed inside square brackets ([]), separated by commas. In this tutorial, we will learn how we can remove the elements from a list using the Python programming language.

We will use multiple ways to remove elements from a list including remove() method, pop() method, clear() method, and del keyword using various examples. Moreover, we will also learn how we can remove duplicate elements and the elements that meet a certain condition. In a nutshell, this tutorial contains all the possible ways to remove the elements from the python list.

Getting started with Python remove element from list

Before learning how we can remove elements from the python list, let us first recap how we can create a list in Python. You can read more about lists from the article on Python lists (Please link to Python list here if any). See the example below where we had created a python list and printed it.

Notice that in the example above, we have created different lists that contain different data typed elements and then we printed those lists. In the following sections, we will discuss how we can remove the elements from the list in various ways.

Python remove element from list using remove() method

Python List type provides the remove() method as a built-in method to remove items from the current list. The remove() method provides very simple usage where the item or object we want to remove is provided to the remove() method as a parameter. The following is the simple syntax of the python remove() method.

The remove() method takes the element or item of list as an argument and removes that element from the list.

Example-1 Remove single element from list

Now let us take an example and see how we can remove an element from a list using this method. In the following example, we have a list of students and let say we want to remove ‘Bashir’ from the list.

Notice that in the output the student name ‘Bashir’ has been removed because we provided it as an argument to the remove() method.

Example-2 Remove multiple elements from a list

We can use Python remove() method to remove all duplicate elements from a list. See the following example where we use the Python while loop and remove() method to remove all the duplicate elements from a list.

So the while loop will be executed unless there will be no 5 in the list, and we are using the python remove() method inside the while loop to remove the element each time the loop is executed.

Example-3 Remove element from list that does not exist

Now let us use the same method to remove an element from a list that does not exist. See the following example where we are trying to remove the number 10 from the list.

Notice that we get an error that says that the provided argument is not in the list.

Python remove element from list using clear() method

Python clear() method removes all the elements from the list. It clears the list completely and returns nothing. The following is the simple syntax of the Python clear() method.

It does not require any parameter and returns no exception if the list is already empty. In this section, we will take examples and see how clear() method works.

Example of using clear() method

As we already said, the clear method removes all the elements from the list at once and returns an empty list. See the example below:

Notice that our list becomes empty because of the clear method which removes all the elements at once. If we will apply the same method on an empty list, then it will return the same list without any error. See the example below:

So, when we apply the clear method on the empty list, it will return the same empty list without any error.

Python remove elements from list using pop() method

This method can take only one optional argument which is the position of the element.

Example of using pop() method

Now let us take an example and see how the Python pop method works. See the Python program below:

Notice that the element on index 2 which was 3 has been removed from the list. If we will not specify the index position, then by default the last element will be removed. See the example below:

Notice that we did not has provided the index position and by default, the last element from the list has been removed.

Python remove element from list using del keyword

The del keyword in python is primarily used to delete objects in Python. Since everything in python represents an object in one way or another, The del keyword can also be used to delete a list, slice a list, delete dictionaries, remove key-value pairs from a dictionary, delete variables, etc. The following is the simple syntax of removing elements from a list using the del keyword.

If we will not specify the index position of a list, then instead of removing element, the del keyword will remove the whole list.

Example-1 Remove single element from list

Now let us take an example and see how we can use the del keyword to remove an element from a list. See the example below:

Notice that the element on index 3 has been removed by the del keyword.

Example-2 Remove multiple elements from a list

We can also remove multiple elements at a time from a list using the del keyword. We have to first specify the elements index positions that we want to remove or in simple words, we have to slice our list and remove the sliced part using the del keyword. See the example below:

Notice that we slice our list and remove the sliced part. All the elements from index position 3 up to 6 have been removed.

Example-3 Remove the whole list

As we already discussed that if we will not specify the index position, then the del keyword will remove the whole list from our program. See the Python program below:

Although we have defined the list at the beginning of our program, then we used the del keyword to remove the list and it deleted the whole list from our program.

Python remove element from list that meets a certain condition

Removing items that satisfy the condition is equivalent to extracting items that do not satisfy the condition. And that is why the List comprehensions are used. You can read more about list comprehension from the article on Python List Comprehension. Now let us take an example and see how we can remove the elements that meet a certain condition.

Notice that we had successfully removed all the odd elements from our list using the list comprehension method.

Summary

In this tutorial, we learned about the Python remove element from list using various methods. We discussed some of the build-in methods that are used to remove elements from a list. For example, Python remove() method, pop() and clear() method. At the same time, we learned how we can remove multiple elements that meet a certain condition by using the list comprehension method. Moreover, we will discuss the del keyword, which is used to delete objects in Python. We solved various examples of removing elements and lists from our program using the del keyword.

Further Reading

Related Posts

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