Prerequisite: List in Python Show As we know Array is a collection of items stored at contiguous memory locations. In Python, List (Dynamic Array) can be treated as Array. In this article, we will learn how to initialize an empty array of some given size. Let’s see different Pythonic ways to do this task. Method 1 – Syntax: list1 = [0] * size list2 = [None] * size
Output: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0] [None, None, None, None, None, None, None, None, None, None] ['A', 'A', 'A', 'A', 'A'] [] Syntax: a = [0 for x in range(size)] #using loops
Output: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0] [[None, None], [None, None]]
Output: [None None None None None] [[None None None None None] [None None None None None]]Article Tags :
This post will discuss how to create an empty list with a given size in Python. To assign any value to a list using the assignment operator at position i, a[i] = x, the list’s size should be at least i+1. Otherwise, it will raise an IndexError, as shown below:
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Download Run Code Which solution to use?The first solution works well for non-reference types like numbers. But you might run into referencing errors in some cases. For example, [[]] * 5 will result in the list containing the same list object repeated 5 times.
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Thanks for reading. Please use our online compiler to post code in comments using C, C++, Java, Python, JavaScript, C#, PHP, and many more popular programming languages. Like us? Refer us to your friends and help us grow. Happy coding 🙂 This tutorial demonstrates ways on how to initialize an empty list in Python. This will cover defining a list of size n or defining a variable-sized list with the values all defaulting to empty. When you declare a list in Python, it always starts off at size 0 since there is no explicit way of declaring a Python list’s size since Python lists are variable in nature. This tutorial will provide a way to initialize a fixed-size list with all the values defaulted to None or empty. Initializing n-Sized None Values to a List in PythonThe best way to solve this problem is to initialize an n-Sized list with the values all set to None, which indicates that a value is empty in Python. To do this, initialize a singleton list with the value None and multiply it by n, which is the list’s preferred size. n = 15 #Size of the List lst = [None] * n print(lst)Output: [None, None, None, None, None, None, None, None, None, None, None, None, None, None, None]The output is a list of size 15 as defined by n with all the values set to None, equivalent to an empty value. This solution is the easiest and most practical way to initialize a list with empty values in Python. However, this is a workaround to the predefined nature of a Python list being variable in size. DelftStack articles are written by software geeks like you. If you also would like to contribute to DelftStack by writing paid articles, you can check the write for us page. Related Article - Python List |