Are lists of function calls allowed in python?
W3Schools is optimized for learning and training. Examples might be simplified to improve reading and learning. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use, cookie and privacy policy. Show Copyright 1999-2022 by Refsnes Data. All Rights Reserved. Question: Is it possible to call a function inside a list comprehension statement? Background: List comprehension is a compact way of creating lists. The simple formula is
For example, the code Related article: List Comprehension in Python — A Helpful Illustrated Guide So, can you use a function with or without return value as an expression inside a list comprehension? Answer: You can use any expression inside the list comprehension, including functions and methods. An expression can be an integer Here’s an example: [print('hi') for _ in range(10)] ''' hi hi hi hi hi hi hi hi hi hi ''' You use the throw-away underscore [print(i) for i in range(10)] ''' 0 1 2 3 4 5 6 7 8 9 ''' Let’s have a look at the content of the list you just created: lst = [print(i) for i in range(10)] print(lst) # [None, None, None, None, None, None, None, None, None, None] The list contains ten Walrus OperatorPython 3.8 has introduced the walrus operator, also known as the
assignment expression. This operator is useful if executing a certain function has side effects that you don’t want. For example, if you have a string creation method inside the list comprehension statement, conditioned by some filtering criterion in the if suffix. Without the walrus operator, Python would execute this same routine multiple times—even though this is highly redundant. You can avoid
this redundancy by assigning it to a variable import random def get_random_string(): return f'sss {random.randrange(0, 100)}' # Goal: Print all random strings that contain 42 # WRONG lst = [get_random_string() for _ in range(1000) if '42' in get_random_string()] print(lst) # ['sss 74', 'sss 13', 'sss 76', 'sss 13', 'sss 92', 'sss 96', 'sss 27', 'sss 43', 'sss 80'] # CORRECT lst = [s for _ in range(1000) if '42' in (s := get_random_string())] print(lst) # ['sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42', 'sss 42'] With the walrus operator I teach these concepts in my exclusive FINXTER email academy—join us, it’s free! Related Video: List ComprehensionA Simple Introduction to List Comprehension in Python While working as a researcher in distributed systems, Dr. Christian Mayer found his love for teaching computer science students. To help students reach higher levels of Python success, he founded the programming education website Finxter.com. He’s author of the popular programming book Python One-Liners (NoStarch 2020), coauthor of the Coffee Break Python series of self-published books, computer science enthusiast, freelancer, and owner of one of the top 10 largest Python blogs worldwide. His passions are writing, reading, and coding. But his greatest passion is to serve aspiring coders through Finxter and help them to boost their skills. You can join his free email academy here. Can I call function from list in Python?Answer. Yes, the variable in the for of a list comprehension can be used as a parameter to a function. In this example, the variable number is passed to randint() to calculate a random number between number and 2 * number for the list produced by the comprehension.
Can you call functions in a list?A function can be passed as argument, or you can include a function as an item in a list, or as a value in key:value pair of a dictionary, or item in a set, etc. In this tutorial, we will learn how to add function(s) as item(s) in a list. In other words, we will build a list of functions.
Can you call functions in Python?Python also accepts function recursion, which means a defined function can call itself. Recursion is a common mathematical and programming concept. It means that a function calls itself.
Which operator Cannot be used with list in Python?Class 'list' does not define '__mod__', so the '%' operator cannot be used.
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