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Intermediate Python Techniques

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Using Python Built-in Functions

Here are two more examples demonstrating the use of lambda functions with the filter() and sorted() functions in Python.

Alternatively, you can pass a more complex custom function instead of a lambda to these high-order functions.

filter()

The filter() function is used to create an iterator from elements of an iterable for which a function returns true. Here's an example using filter() with a lambda function to filter out odd numbers from a list:


              
12345678

            
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# Using a lambda function to filter out odd numbers
even_numbers = filter(lambda x: x % 2 == 0, numbers)

# Convert the filter object to a list
even_numbers_list = list(even_numbers)
print(even_numbers_list)
copy

In this example, the lambda function lambda x: x % 2 == 0 checks if a number is even. The filter() function applies this lambda to each element in the list of numbers and returns an iterator of even numbers.

sorted()

The sorted() function returns a new sorted list from the elements of any iterable.

python

  • iterable is the sequence to sort (list, dict, tuple, etc);

  • key is a function to execute to decide the order;

  • reverse is a boolean. False is an ascending order, and True is descending. The default is False.

Here's an example using sorted() with a lambda function to sort a list of tuples based on the second element in each tuple:


              
123456

            
tuples = [(1, 'banana'), (2, 'apple'), (3, 'orange')]

# Using a lambda function to sort by the second element of each tuple
sorted_tuples = sorted(tuples, key=lambda x: x[1])

print(sorted_tuples)
copy

In this example, the lambda function lambda x: x[1] returns the second element of each tuple. The sorted() function then sorts the list tuples based on these second elements, resulting in a list sorted alphabetically by the fruit names.

Oppgave

Swipe to start coding

Let's consider a list of dictionaries representing books, and you want to filter out books that have a certain number of pages.

  1. Define the list of books. books is a list of dictionaries. Each dictionary represents a book with two keys: "title" and "pages".
  2. Creating the custom function has_many_pages that accepts book and min_pages arguments.
  3. Use filter() with the custom function.
  4. Converte the filter object to a list, store it to the filtered_books_list variable, and print it.

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book
Using Python Built-in Functions

Here are two more examples demonstrating the use of lambda functions with the filter() and sorted() functions in Python.

Alternatively, you can pass a more complex custom function instead of a lambda to these high-order functions.

filter()

The filter() function is used to create an iterator from elements of an iterable for which a function returns true. Here's an example using filter() with a lambda function to filter out odd numbers from a list:


              
12345678

            
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# Using a lambda function to filter out odd numbers
even_numbers = filter(lambda x: x % 2 == 0, numbers)

# Convert the filter object to a list
even_numbers_list = list(even_numbers)
print(even_numbers_list)
copy

In this example, the lambda function lambda x: x % 2 == 0 checks if a number is even. The filter() function applies this lambda to each element in the list of numbers and returns an iterator of even numbers.

sorted()

The sorted() function returns a new sorted list from the elements of any iterable.

python

  • iterable is the sequence to sort (list, dict, tuple, etc);

  • key is a function to execute to decide the order;

  • reverse is a boolean. False is an ascending order, and True is descending. The default is False.

Here's an example using sorted() with a lambda function to sort a list of tuples based on the second element in each tuple:


              
123456

            
tuples = [(1, 'banana'), (2, 'apple'), (3, 'orange')]

# Using a lambda function to sort by the second element of each tuple
sorted_tuples = sorted(tuples, key=lambda x: x[1])

print(sorted_tuples)
copy

In this example, the lambda function lambda x: x[1] returns the second element of each tuple. The sorted() function then sorts the list tuples based on these second elements, resulting in a list sorted alphabetically by the fruit names.

Oppgave

Swipe to start coding

Let's consider a list of dictionaries representing books, and you want to filter out books that have a certain number of pages.

  1. Define the list of books. books is a list of dictionaries. Each dictionary represents a book with two keys: "title" and "pages".
  2. Creating the custom function has_many_pages that accepts book and min_pages arguments.
  3. Use filter() with the custom function.
  4. Converte the filter object to a list, store it to the filtered_books_list variable, and print it.

Løsning

Switch to desktopBytt til skrivebordet for virkelighetspraksisFortsett der du er med et av alternativene nedenfor
Alt var klart?

Hvordan kan vi forbedre det?

Takk for tilbakemeldingene dine!

Seksjon 3. Kapittel 3
Switch to desktopBytt til skrivebordet for virkelighetspraksisFortsett der du er med et av alternativene nedenfor
Vi beklager at noe gikk galt. Hva skjedde?
some-alt