Dictionary Comprehensions

Dictionary comprehensions provide a concise and elegant way to create dictionaries in Python. They follow a similar structure to list comprehensions but with some key differences.

Basic Dictionary Comprehension

At its heart, a basic dictionary comprehension lets you construct a new dictionary by applying an expression to each key-value pair in an iterable variable.

Syntax:

key_expression: defines the key for each key-value pair;
value_expression: defines the value corresponding to the key;
iterable: the source of items to be processed (e.g., a list, range, or another iterable).

Note

Unlike lists, dictionaries require both a key and a value, separated by a colon (:) and use {} instead of [].


              1234567891011
            
books = [
    ("Pride and Prejudice", 1813),
    ("1984", 1949),
    ("To Kill a Mockingbird", 1960),
    ("The Great Gatsby", 1925)
]

# Create a dictionary using dictionary comprehension
book_dict = {title: year for title, year in books}

print(book_dict)

For each tuple in the books list, the title is used as the key, and the year is used as the value.

The same dictionary can be created using a for loop:


              123456789101112
            
books = [
    ("Pride and Prejudice", 1813),
    ("1984", 1949),
    ("To Kill a Mockingbird", 1960),
    ("The Great Gatsby", 1925)
]

book_dict = {}
for title, year in books:
    book_dict[title] = year

print(book_dict)

Task

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A bookstore wants to create a dictionary that maps book titles to their prices. Use dictionary comprehension to create a new dictionary called book_prices from the following list of lists:

Transform the books list into a dictionary using dictionary comprehension, where the title is the key, and the price is the value.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

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Section 2. Chapter 10

Dictionary Comprehensions

Dictionary comprehensions provide a concise and elegant way to create dictionaries in Python. They follow a similar structure to list comprehensions but with some key differences.

Basic Dictionary Comprehension

At its heart, a basic dictionary comprehension lets you construct a new dictionary by applying an expression to each key-value pair in an iterable variable.

Syntax:

key_expression: defines the key for each key-value pair;
value_expression: defines the value corresponding to the key;
iterable: the source of items to be processed (e.g., a list, range, or another iterable).

Note

Unlike lists, dictionaries require both a key and a value, separated by a colon (:) and use {} instead of [].


              1234567891011
            
books = [
    ("Pride and Prejudice", 1813),
    ("1984", 1949),
    ("To Kill a Mockingbird", 1960),
    ("The Great Gatsby", 1925)
]

# Create a dictionary using dictionary comprehension
book_dict = {title: year for title, year in books}

print(book_dict)

For each tuple in the books list, the title is used as the key, and the year is used as the value.

The same dictionary can be created using a for loop:


              123456789101112
            
books = [
    ("Pride and Prejudice", 1813),
    ("1984", 1949),
    ("To Kill a Mockingbird", 1960),
    ("The Great Gatsby", 1925)
]

book_dict = {}
for title, year in books:
    book_dict[title] = year

print(book_dict)

Task

Swipe to show code editor

A bookstore wants to create a dictionary that maps book titles to their prices. Use dictionary comprehension to create a new dictionary called book_prices from the following list of lists:

Transform the books list into a dictionary using dictionary comprehension, where the title is the key, and the price is the value.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 10

Switch to desktop for real-world practiceContinue from where you are using one of the options below