List Data in Python with example

How to store multiple data in one variable?

The answer is using a List.

A list is a data structure in python capable of storing more than one piece of data, such as an array.

On this occasion, we will discuss how to use lists in Python from the simplest to the least complex.

What are the points to be studied?

• How to make a List and fill it

• How to extract values from a List

• How to add and remove List contents

• Operations on lists

• Multi-dimensional List

Happy learning…

How to create a List in Python

We can make a List like a regular variable, but the value of the variable is filled with square brackets []. 

Examples:

# Create an empty list

color = []

# Create a list with one item

hobby = ["reading"]

If the list has more than one content, then we can separate them with commas.

Examples:

fruits = ["orange", "apple", "mango", "papaya"]

What types of data can be included in a List?

The List can be filled with any data type, string, integer, float, double, boolean, object, and so on.

We can also mix the filling.

Examples:

store = ["book", 21, True, 34.12]

There are four types of data in a list store:

1. "book" is a string data type;

2. 21 is an integer data type;

3. True is a boolean data type;

4.  34.12

How to retrieve values from a List

Now that we know how to create and store data in a List, let's try to retrieve the data.

Just like arrays, lists also have Index numbers to access the data or its contents.

Colors =

“Red”

“Green”

“Yellow”

    0                     1                         3

List Index numbers always start at zero (0).

This index number is what we need to retrieve the contents (items) of the list.

Examples:

# We have a list of fruits

fruits = ["apple", "grapes", "mango", "orange"]

# For example we will take a mango, then the index is 2

print fruits[2]

Will produce the output:

"mango"

Hooray! got a mango. 😄

Exercise 1: Create a Program with a List

To establish understanding, please try the following exercise.

• Make a list to keep your contacts

• Fill in the list of 5

• Show contents of Index list number 3

• Show all friends with looping

• Show list length

Let's try the code below …

# Create a list to store the names of friends

my_friends = ["Anggun", "Diana", "Melly", "Jhon", "Adam"]

# Display the contents of the my_friends list with index number 3

print("The content of the 3rd index my_friends is: {}".format(my_friends[3]))

# Show all friends

print("All friends are there {} person".format(len(my_friends)))

for friend in my_friends:

    print(friend)      

In the code above, we use the function len() to take a long list.
Output results:

Changing The List Value

Lists are mutable, meaning they can be changed.

Examples:

# First list look like below

fruits = ["apple", "grapes", "mango", "orange"]

# Change the value of index to 2

fruits[2] = "coconut"

It "mango" will be replaced with "coconut".

["apple", "grapes", "coconut", "orange"]

Adding A List Item

There are three methods or functions that can be used to add content or items to a List:

1. append(item) add items from the back.

2. insert(index, item) adding items from a specific index

Examples:

# First the list are

fruits = ["apple", "grapes", "mango", "orange"]

# Adding mangosteen

fruits.append("mangosteen")

print(fruits)

The result "mangosteen" will be added after the last item. Look result at below:

The second method uses insert().

The method insert() will add items to a specific index of the list.

Examples:

# First the list is

fruits = ["apple", "grapes", "mango", "orange"]

# Adding mangosteen

fruits.insert(1,"mangosteen")

print(fruits)

The result "mangosteen" will be added after the last item. Look result at below:

Delete an Item in the List

To remove one of the contents of the List, we can use the command del.

The command del deletes a variable from memory.

Examples:

# Create List

todo_list = [

"Learn Python",

"Learn Django",

"Learn MongoDB",

"Learn Magic",

"Learn Flask"

]

# Suppose we want to remove "Learn Magic"

# which is on the 3rd index

del todo_list[3]

print(todo_list)

 

Look the output at below:

As a result, "Learn Magic" will be deleted:

In addition to using the command del, we can also use the method remove() with the item parameter that will be deleted.

Examples:

# First we have a list

a = ["a", "b", "c", "d"]

# then delete b

a.remove("b")

print(a)

Results :

Actually, there is still a lot I want to discuss about the list, but since this article is quite long... 

I end it here.

Next, please experiment yourself with the list.

#Python

 

January 08, 2023