You can use:
>>> lst = [None] * 5
>>> lst
[None, None, None, None, None]
Top answer 1 of 11
450
You can use:
>>> lst = [None] * 5
>>> lst
[None, None, None, None, None]
2 of 11
112
Why don't these questions get answered with the obvious answer?
a = numpy.empty(n, dtype=object)
This creates an array of length n that can store objects. It can't be resized or appended to. In particular, it doesn't waste space by padding its length. This is the Python equivalent of Java's
Object[] a = new Object[n];
If you're really interested in performance and space and know that your array will only store certain numeric types then you can change the dtype argument to some other value like int. Then numpy will pack these elements directly into the array rather than making the array reference int objects.
GeeksforGeeks
geeksforgeeks.org › python › python-initialize-empty-array-of-given-length
Python - Initialize empty array of given length - GeeksforGeeks
As we know Array is a collection of items stored at contiguous memory locations. In Python, a List (Dynamic Array) can be treated as an Array. In this article, we will learn how to initialize an empty array of some given size. Let's see different Pythonic ways to create an empty list in Python with a certain size.
Published July 12, 2025
python 3.x - Initializing a numpy array of arrays of different sizes - Stack Overflow
What I want to do, is to create a numpy array having 1 row and 3 coulmns. Now I want to fill up the array, such that every element of the array are arrays themselves. And not only that, the size... More on stackoverflow.com
learning to declare and initialize arrays in a single line of code
okay i like LINQ. Like... a lot. To a problematic degree. But this is a fucking war crime. Bro woke up and didn't choose violence. They chose genocide. More on reddit.com
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153
December 30, 2024Is it possible to create an array in python?
I noticed that python uses Linked Lists by default It does not. Python's list type is a dynamically growing array, similar to vectors in C++, ArrayLists in Java, Lists in C# or arrays in Ruby, Perl, PHP or JavaScript. More on reddit.com
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1
May 2, 2024Aren’t variables initialised in Python?
I'm confused - I didn't think you coul declare a variable in Python without initializing it with something. What exactly do you mean? More on reddit.com
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December 24, 2021Videos
AskPython
askpython.com › home › 3 ways to initialize a python array
3 ways to initialize a Python Array - AskPython
January 16, 2024 - We have created an array — ‘arr’ and initalized it with 5 elements carrying a default value (0). ... Python NumPy module can be used to create arrays and manipulate the data in it efficiently. The numpy.empty() function creates an array of a specified size with a default value = ‘None’.
Quora
quora.com › How-do-I-create-an-array-of-a-specific-size-in-Python
How to create an array of a specific size in Python - Quora
Answer (1 of 3): (1) In Python, you don’t typically work with arrays, but with lists. There are libraries to work with arrays, but you only use them for certain specialized purposes. Such as when you need matrix multiplication or some other advanced math, and want to do it quickly.
Quora
quora.com › In-Python-how-can-I-initialize-an-array-or-list-yet-to-be-populated-with-values-to-have-a-defined-size
In Python, how can I initialize an array (or list), yet to be populated with values, to have a defined size? - Quora
True: you didn’t find any contradictions; this behavior is standard in the Python library and most other collections libraries I’ve worked with · False: a kind of soft error indicator for an empty input ... raise an exception: raising exceptions is effectively an output value - just one that gets handled differently from normal program flow ... It’s easy enough to modify both to get true: just return True if the collection is empty right off the bat. ... RelatedHow do I initialize an array with a specific size in Python (like Roblox Luau's table.create (size, value) or LuaJIT's table.new (size, value) for example)?
W3Schools
w3schools.com › python › python_arrays.asp
Python Arrays
Note: Python does not have built-in support for Arrays, but Python Lists can be used instead. Note: This page shows you how to use LISTS as ARRAYS, however, to work with arrays in Python you will have to import a library, like the NumPy library.
TutorialsPoint
tutorialspoint.com › article › how-to-initialize-an-empty-array-of-given-length-using-python
How to Initialize an Empty Array of given Length using Python
March 27, 2026 - Use multiplication operator [None] * length for simple empty arrays. For numerical computations, prefer NumPy's empty() function. List comprehension offers flexibility for complex initialization patterns.
NumPy
numpy.org › devdocs › user › basics.creation.html
Array creation — NumPy v2.5.dev0 Manual
In the third example, the array is dtype=np.float64 to accommodate the step size of 0.1. Due to roundoff error, the stop value is sometimes included. numpy.linspace will create arrays with a specified number of elements, and spaced equally between the specified beginning and end values.
NumPy
numpy.org › doc › stable › user › basics.creation.html
Array creation — NumPy v2.4 Manual
In the third example, the array is dtype=float to accommodate the step size of 0.1. Due to roundoff error, the stop value is sometimes included. numpy.linspace will create arrays with a specified number of elements, and spaced equally between the specified beginning and end values.
Note.nkmk.me
note.nkmk.me › home › python
Initialize a List of Any Size with Specific Values in Python | note.nkmk.me
August 20, 2023 - This article explains how to initialize a list of any size (number of elements) with specific values in Python. ... See the following article about initializing a NumPy array (numpy.ndarray).
Python
docs.python.org › 3 › library › array.html
array — Efficient arrays of numeric values
The actual size can be accessed through the array.itemsize attribute. ... A string with all available type codes. ... A new array whose items are restricted by typecode, and initialized from the optional initializer value, which must be a bytes or bytearray object, a Unicode string, or iterable over elements of the appropriate type.
Kristianeschenburg
kristianeschenburg.github.io › 2019 › 08 › list-size
Quick Note: Initialize Python List With Prespecified Size - A Rambling On
August 21, 2019 - # For simplicity assume we have 10 items known_size = 10 initialized_list = [None]*known_size print(len(initialized_list)) 10 · Neat, huh? And ridiculously simple. Now, rather than append, we can do the following: for j, temp_file in enumerate(list_of_files): loaded_file = load_file(temp_file) initialized_list[j] = loaded_file · Because the memory has already been pre-allocated, the resize method is never accessed, and we save time. I also found this blog post with some information about timing with regards to Numpy arrays, lists, and tuples – the author shows that indexing into a Numpy array is actually slower than indexing into a list.
YouTube
youtube.com › business analytics tutorials
Intro to Python Part I: Creating and Initializing Arrays - YouTube
This video makes an introduction to Python. The focus is to define arrays using NumPy, initialize its values, update certain elements, and use "print" functi...
Published February 2, 2022 Views 256
Finxter
blog.finxter.com › 5-best-ways-to-create-a-numpy-array-of-size-n-in-python
5 Best Ways to Create a NumPy Array of Size N in Python – Be on the Right Side of Change
For more general array initializations where each element is a specific number other than zero or one, the numpy.full() function fills the bill. This versatile function accepts the array size and the number to fill the array with, accommodating diverse initialization needs.
FavTutor
favtutor.com › blogs › how-to-initialize-an-array-in-python
How to Initialize an Array in Python? (with Code) | FavTutor
January 27, 2021 - Python language has many inbuilt libraries and functions which makes our task easier and simpler in comparison to other programming languages. NumPy module is one of them. NumPy module can be used to initialize the array and manipulate the data stored in it. The number.empty() function of the NumPy module creates an array of a specified size with the default value=” None”.
Vultr Docs
docs.vultr.com › python › third-party › numpy › empty
Python Numpy empty() - Create Empty Array | Vultr Docs
November 18, 2024 - This code initializes an array of length 3 with indeterminate values.
W3Schools
w3schools.com › Python › numpy › numpy_creating_arrays.asp
NumPy Creating Arrays
NumPy is used to work with arrays. The array object in NumPy is called ndarray. We can create a NumPy ndarray object by using the array() function. import numpy as np arr = np.array([1, 2, 3, 4, 5]) print(arr) print(type(arr)) Try it Yourself » · type(): This built-in Python function tells us the type of the object passed to it.
NumPy
numpy.org › doc › 2.2 › reference › routines.array-creation.html
Array creation routines — NumPy v2.2 Manual
empty(shape[, dtype, order, device, like]) · Return a new array of given shape and type, without initializing entries
Studytonight
studytonight.com › python-howtos › how-to-declare-an-array-in-python
How to declare an array in Python - Studytonight
July 21, 2023 - But you can create a simple array using a Python list and add some values to it to initialize the array size. ... In the code example above, both arr1 and arr2 have size 3. Q. How to fill array in Python? There are many ways to create an array in Python and fill an array with values in Python.