[Tut] 6 Ways to Remove Python List Elements

[xSicKxBot]

6 Ways to Remove Python List Elements

5/5 – (2 votes)

Problem Formulation and Solution Overview

This article will show you how 6 ways to remove

Code:

List

elements in Python.

To make it more interesting, we have the following running scenario:

Suppose you have a Christmas [i]

Code:

List

[/i] containing everyone to buy a gift for. Once a gift is purchased, remove this person from the

Code:

List

. Once all gifts have been purchased, remove the entire

Code:

List

.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn']

Question: How would we write code to remove items from a Python List?

We can accomplish this task by one of the following options:

• Method 1: Use the
  Code:

  del
  Keyword
  
  
• Method 2: Use
  Code:

  remove()
  and a
  Code:

  for
  Loop
  
  
• Method 3: Use slicing
  
  
• Method 4: Use
  Code:

  pop()
  
  
  
• Method 5: Use List Comprehension
  
  
• Method 6: Use
  Code:

  clear()
  
  

Method 1: Use the del Keyword

This method uses Python’s

Code:

del

Keyword and highlights its ability to remove one List element and all List elements.

Remove One List Element

In this scenario,

Code:

Asa's

gift has been purchased and will be removed from the

Code:

List

.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] del xmas_list[3] print(xmas_list)

As shown on the highlighted line,

Code:

Asa

is removed from the List by using

Code:

del

, referencing

Code:

xmas_list

and specifying Asa’s location (

Code:

[3]

).

When

Code:

xmas_list

is output to the terminal, the following displays.

Code:

['Anna', 'Elin', 'Inger', 'Sofie', 'Gunnel', 'Linn']

Remove All List Elements

In this scenario, all gifts have been purchased, and all List elements will be removed.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] del xmas_list print(xmas_list)

As shown on the highlighted line, all elements of

Code:

xmas_list

are removed by using

Code:

del

and referencing

Code:

xmas_list

.

When

Code:

xmas_list

is output to the terminal, the following error is generated.

Code:

NameError: name 'xmas_list' is not defined

Note: This error is generated because the variable

Code:

xmas_list

no longer exists in memory.



Method 2: Use remove() and a For Loop

This example uses the

Code:

remove()

function in conjunction with a

Code:

for

loop to remove one List element and all List elements.

Remove One List Element

In this scenario,

Code:

Elin's

gift has been purchased and will be removed from the List.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] xmas_list.remove('Elin') print(xmas_list)

As shown on the highlighted line,

Code:

Elin

is removed from the List using the

Code:

remove()

function and passing Elin’s name as an argument.

When

Code:

xmas_list

is output to the terminal, the following displays.

Code:

['Anna', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn']

Remove All List Elements

In this scenario, all gifts have been purchased, and all

Code:

List

elements will be removed.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] for item in xmas_list.copy(): xmas_list.remove(item) print(xmas_list)

As shown on the first highlighted line, a

Code:

for

loop is instantiated. This loop declares a shallow copy of the List to iterate.

On each iteration, the

Code:

remove()

function is called and passed the current name in

Code:

xmas_list

as an argument (see below) and removed.

For example:

Code:

AnnaElinIngerAsaSofieGunnelLinn

When

Code:

xmas_list

is output to the terminal, an empty

Code:

List

displays.

Code:

[]

Note: A shallow copy creates a reference to the original List. For further details, view the video below.



Method 3: Use slicing

This method uses slicing to remove one List element and all List elements.

Remove One List Element

In this scenario,

Code:

Anna's

gift has been purchased and will be removed from the List.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] xmas_list = xmas_list[1:] print(xmas_list)

As shown on the highlighted line,

Code:

Anna

is removed from the

Code:

List

using

Code:

slicing

.

When

Code:

xmas_list

is output to the terminal, the following displays.

Code:

['Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn']

Remove All List Elements

In this scenario, all gifts have been purchased, and all

Code:

List

elements will be removed.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] xmas_list = [] print(xmas_list)

As shown on the highlighted line, all

Code:

List

elements are removed by declaring an empty

Code:

List

.

When

Code:

xmas_list

is output to the terminal, an empty

Code:

List

displays.

Code:

[]

Method 4: Use pop()

This method uses the

Code:

pop()

function to remove one List element and all List elements.

Remove One List Element

In this scenario,

Code:

Linn's

gift has been purchased and will be removed from the

Code:

List

.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] xmas_list.pop() xmas_list.pop(2) print(xmas_list)

As shown on the first highlighted line, the

Code:

pop()

method is appended to the

Code:

xmas_list

. This lets Python know to remove a List element from said List. Since no element is specified, the last element is removed (

Code:

Linn

).

On the second highlighted line, the

Code:

pop()

method is appended to the

Code:

xmas_list

and passed one (1) argument: the element to remove (

Code:

2

). This action removes Inger.

When

Code:

xmas_list

is output to the terminal, the following displays.

Code:

['Anna', 'Elin', 'Asa', 'Sofie', 'Gunnel']

Note: Both Linn and Inger are no longer in

Code:

xmas_list

.

Remove All List Elements

In this scenario, all gifts have been purchased, and all

Code:

List

elements will be removed.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] for i in xmas_list.copy(): xmas_list.pop() print(xmas_list)

As shown on the first highlighted line, a

Code:

for

loop is instantiated. This loop declares a shallow copy of the List to iterate.

On each iteration, the

Code:

pop()

method is called. Since no argument is passed, the last element is removed.

When

Code:

xmas_list

is output to the terminal, an empty List displays.

Code:

[]

Method 5: Use List Comprehension

This method uses List Comprehension to remove all List elements that do not meet the specified criteria.

Remove One List Element

In this scenario,

Code:

Gunnel's

gift has been purchased and will be removed from the List.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] xmas_list = [value for value in xmas_list if value != 'Gunnel'] print(xmas_list)

When

Code:

xmas_list

is output to the terminal, the following displays.

Code:

['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Linn']

Note: To remove all List elements, pass it empty brackets as shown follows: (

Code:

xmas_list = []

).



Method 6: Use clear()

This method uses

Code:

clear()

to remove all List elements.

In this scenario, all gifts have been purchased, and all List elements will be removed.

Code:

xmas_list = ['Anna', 'Elin', 'Inger', 'Asa', 'Sofie', 'Gunnel', 'Linn'] xmas_list.clear() print(xmas_list)

As shown on the highlighted line, all List elements are removed by appending the

Code:

clear()

function to

Code:

xmas_list

.

When

Code:

xmas_list

is output to the terminal, an empty List displays.

Code:

[]

Summary

This article has provided six (6) ways to remove List elements to select the best fit for your coding requirements.

Good Luck & Happy Coding!

Programming Humor

Programming is 10% science, 20% ingenuity, and 70% getting the ingenuity to work with the science.

~~~

• Question: Why do Java programmers wear glasses?
  
  
• Answer: Because they cannot C# …!
  

Feel free to check out our blog article with more coding jokes.