Python - Understanding Lists, Tuples, Sets, and Dictionaries

Lists, Tuples, Sets, and Dictionaries in Python

Python has several built-in data types for various data handling and storage forms. The most popular ones for storing collections of data are dictionaries, sets, tuples, and lists. They are all appropriate for different Python programming scenarios because of their unique qualities and application cases.

Understanding Python Collections

The following is the list of Python collections:

Tuple

The tuple is a data type in Python. It is an immutable, ordered collection of items. Once it is created, it can not be modified or changed. 

Creation

Items are entered into parenthesis() and separated with commas to construct tuples.

coordinates = (10.0, 20.0)

Tuples are a safer option for fixed collections of elements because of their immutability—they cannot be changed after formation.

Use Cases

Tuples are useful when storing a group of values, such as coordinates or dates, that shouldn't change while the application runs.

Example

Here, is an example of tuples:

# Creating a tuple
coordinates = (10.0, 20.0)
print(coordinates) # Output: (10.0, 20.0)

# Accessing an item from the tuple
print(coordinates[0]) # Output: 10.0

# Trying to change an item (this will raise an error)
# coordinates[0] = 15.0 # Uncommenting this line will raise a TypeError

List

When arranging elements of different data kinds, a list in Python is called such. The items of a list can be altered after it is generated, which makes lists changeable. In a list, it is possible to add, delete, or alter things in it.

Creation

Items are entered inside square brackets [], and commas are used to separate them.

fruits = ["apple", "banana", "cherry"]

Use Cases

Use lists when you need to add, remove, or update things from a collection of objects that are in order regularly.

Example

Here, is an example of a list:

#Creating a list
fruits = ["apple", "banana", "cherry"]
print(fruits) #Output: ['apple', 'banana', 'cherry']

#Adding an item to the list
fruits.append("orange")
print(fruits) #Output: ['apple', 'banana', 'cherry', 'orange']

#Accessing an item from the list
print(fruits[1]) #Output: banana

#Removing an item from the list
fruits.remove("banana")
print(fruits) #Output: ['apple', 'cherry', 'orange']

Set

In Python, a set is an unordered grouping of distinct objects. Duplicates are automatically eliminated, and sets are modifiable.

Creation

You can construct sets by using the set() method or by putting items inside curly braces {} and separating them with commas.

unique_numbers = {1, 2, 3, 3, 4}

Use Cases

Use sets to do set operations such as union, intersection, and difference, or ensure no duplicate items exist in your collection.

Example

Here, is an example of the set:

# Creating a set
unique_numbers = {1, 2, 3, 3, 4}
print(unique_numbers) # Output: {1, 2, 3, 4} - duplicates are removed

# Adding an item to the set
unique_numbers.add(5)
print(unique_numbers) # Output: {1, 2, 3, 4, 5}

# Removing an item from the set
unique_numbers.remove(2)
print(unique_numbers) # Output: {1, 3, 4, 5}

Dictionary

A dictionary is an ordered collection of key-value pairs, where each key is unique and maps to a specific value, we can also call the dictionary an associative array, Hash, and map.

Creation

Key-value pairs are enclosed in curly brackets {} to build dictionaries, with colons between the keys and values.

person = {"name": "John", "age": 30}

Key-Value Pair

Keys, not positions, are used in dictionaries to access values. Dictionaries can have their contents modified after they are constructed, which is known as mutability.

Example

Here, is an example of the dictionary:

# Creating a dictionary
person = {"name": "John", "age": 30}
print(person) # Output: {'name': 'John', 'age': 30}

# Adding or updating a key-value pair
person["city"] = "New York"
print(person) # Output: {'name': 'John', 'age': 30, 'city': 'New York'}

# Accessing a value by key
print(person["name"]) # Output: John

# Removing a key-value pair
del person["age"]
print(person) # Output: {'name': 'John', 'city': 'New York'}