create empty 2d list python - Brave Search

Creating a 2d matrix in python [duplicate]

stackoverflow.com › questions › 4230000 › creating-a-2d-matrix-in-python

Using nested comprehension lists :

x = [[None for _ in range(5)] for _ in range(6)]

Answer from Vincent Savard on Stack Overflow

quora.com › How-do-you-create-an-empty-2D-list-in-Python

How to create an empty 2D list in Python - Quora

Answer (1 of 10): C̲r̲e̲a̲t̲i̲n̲g̲ ̲a̲n̲ e̲m̲p̲t̲y̲ ̲2̲D̲ ̲li̲s̲t̲ ̲i̲n̲ ̲P̲y̲t̲h̲o̲n̲ ̲i̲s̲ ̲s̲t̲r̲a̲i̲g̲h̲t̲f̲o̲r̲w̲ar̲d̲ ̲,̲ ̲b̲u̲t̲ ̲u̲n̲d̲e̲r̲s̲t̲a̲n̲di̲n̲g̲ ̲t̲h̲e̲ ̲n̲u̲a̲n̲c̲e̲s̲ ̲e̲ns̲u̲r̲e̲s̲ ...

Statistics Globe

statisticsglobe.com › home › python programming language for statistics & data science › create empty 2d list in python (2 examples)

Create Empty 2D List in Python (2 Examples) | Zero Elements

March 31, 2023 - With the second loop, we created columns of “None” values, which corresponded to the number of columns we initialized, and appended that to the rows using the append() method. The rows were then appended to the empty 2D list called “my_list”. Here, we will make use of list comprehension method to generate an empty 2D list in Python:

Discussions

list - Creating a 2d matrix in python - Stack Overflow

How to initialize a two-dimensional array (list of lists, if not using NumPy) in Python? (32 answers) Closed 1 year ago. I create a 6x5 2d array, initially with just None in each cell. I then read a file and replace the Nones with data as I read them. I create the empty array first because ... More on stackoverflow.com

stackoverflow.com

Python create empty 2-dimensional array - Stack Overflow

You get the IndexError because you can't assign to an index in the list beyond the current length of the list. Since grid2 is initialized to an empty list, any attempt to index it will raise this error. More on stackoverflow.com

stackoverflow.com

python - How to define an empty 2 dimensional list instead of data = [["",""],["",""],["",""],["",""]] - Stack Overflow

My approach to this problem would ... for python. In that library, there's a very simple way of accomplishing this. If I want to generate an empty matrix built to hold m rows of n strings, I'd do it like this: import numpy as np # import the library m = 32 n = 16 # choose your array dimensions data = np.empty((m, n), dtype=str) # create the empty ... More on stackoverflow.com

stackoverflow.com

Explain 2D Lists

Lists contain things. Lists are things. Therefore, lists can contain lists. That's literally all there is to it. More on reddit.com

r/learnpython

6

2

August 3, 2014

Videos

Python 2D arrays and lists - YouTube

October 24, 2022

2D List in Python - YouTube

September 18, 2021

Creating two dimensional list in python - YouTube

Creating two dimensional lists (arrays) in Python - YouTube

January 16, 2017

Python 2D collections are easy! ⬜ - YouTube

November 8, 2022

how to create a python 2D list dynamically - YouTube

October 27, 2023

daniweb.com › programming › software-development › threads › 160559 › empty-2d-array

python - Empty 2D Array [SOLVED] | DaniWeb

December 3, 2008 - For heavy numeric work, prefer NumPy arrays for performance and vectorization; initialize once you know dimensions: arr = numpy.zeros((rows, cols)) (NumPy zeros). More on the aliasing gotcha: Python FAQ: multidimensional lists. defaultdict docs: collections.defaultdict. hoe to write a generic code for creating a empty 2D array and dynamically insert values in it.

stackoverflow.com › questions › 4230000 › creating-a-2d-matrix-in-python

list - Creating a 2d matrix in python - Stack Overflow

Using nested comprehension lists :

x = [[None for _ in range(5)] for _ in range(6)]

What's going on here is that the line

x = [[None]*5]*6

expands out to

x = [[None, None, None, None, None, None]]*6

At this point you have a list with 6 different references to the singleton None. You also have a list with a reference to the inner list as it's first and only entry. When you multiply it by 6, you are getting 5 more references to the inner list as you understand. But the point is that theres no problem with the inner list, just the outer one so there's no need to expand the construction of the inner lists out into a comprehension.

x = [[None]*5 for _ in range(6)]

This avoids duplicating references to any lists and is about as concise as it can readably get I believe.

dotnetperls.com › 2d-python

Python - 2D List Examples - Dot Net Perls

Step 1 We first create an empty list with the empty square brackets. Then we call the append method and add 2 empty lists. Step 2 We access each sub-list and call append on it. This appends to the inner lists. Step 3 We display the element at indexes 0, 0 and this value is 1. With the print() ...

python-forum.io › thread-30401.html

Append 2d empty lists

October 19, 2020 - Hi there! I wanted to store my functions result in a 2d list. The function returns 5 values and has to run 100 times in a for loop. I tried to initiate a storage list by ding this: list1 = [[]]*5which returns list1 = [[], [], [], [], []] However, w...

sentry.io › sentry answers › python › define a two-dimensional array in python

Python Define a Two-Dimensional Array or Matrix | Sentry

3 days ago - Create a 2D array in Python using numpy.zeros for matrix operations, or a nested list comprehension if you want to avoid the numpy dependency

Find elsewhere

Google Bing Mojeek

stackoverflow.com › questions › 61008021

Python create empty 2-dimensional array - Stack Overflow

You get the IndexError because you can't assign to an index in the list beyond the current length of the list. Since grid2 is initialized to an empty list, any attempt to index it will raise this error.

One correct way to write your nested list comprehension using for loops would be to construct the inner list first for each row, then append this to grid2:

grid2 = []
for i in range(rows):
    inner = []
    for j in range(cols):
        inner.append(0)
    grid2.append(inner)

you should initialize grid2=np.empty([rows, cols]) instead please refer to https://docs.scipy.org/doc/numpy/reference/generated/numpy.empty.html#numpy.empty for more details

snakify.org › two-dimensional lists (arrays)

Two-dimensional lists (arrays) - Learn Python 3 - Snakify

Another (but similar) way: create an empty list and then append a new element to it n times (this element should be a list of length m):

stackoverflow.com › questions › 72697236 › how-to-define-an-empty-2-dimensional-list-instead-of-data

python - How to define an empty 2 dimensional list instead of data = [["",""],["",""],["",""],["",""]] - Stack Overflow

This is a possible solution:

data = [['' for j in range(m)] for i in range(n)]

m and n are the desired dimensions of your list of lists.

lis = [[] for _ in range(3)] try it

reddit.com › r/learnpython › explain 2d lists

r/learnpython on Reddit: Explain 2D Lists

August 3, 2014 -

Hi redditors!

I'm learning Python and I have to do a project with 2D lists. I'm fairly new to programming and I'm having a hard time understanding the format of a 2D list.

I'm trying to create rows and columns with '.' but I can only print out one row.....can someone help me by giving a simple example on how to do 2D lists, please? Oh, and reddit is my last resource. I have been looking for material I can understand but I'm having trouble :_(

Lists contain things. Lists are things. Therefore, lists can contain lists. That's literally all there is to it.

It may help you visualize it better if you print every row separately: #make an empty list >>>my_2d_list = [] #add the first row >>>my_2d_list.append([1,2,3]) #add the second row >>>my_2d_list.append([4,5,6]) #add the third row >>>my_2d_list.append([7,8,9]) >>>for row in my_2d_list: >>> print row [1, 2, 3] [4, 5, 6] [7, 8, 9] Instead of adding the rows one by one, you can add them all at once like u/Sackboii did. Adding columns is much harder, since python does not require every row to be the same length. Try to avoid that.

oreateai.com › blog › understanding-2d-arrays-in-python-a-practical-guide › 9f5ad1785de4338959c4405e02704471

Understanding 2D Arrays in Python: A Practical Guide - Oreate AI Blog

January 21, 2026 - Here’s how you can do it: Define ... c = 10 # number of columns · Initialize the List: Create an empty list that will eventually hold our sublists (each representing a row)....

pythonguides.com › create-an-empty-array-in-python

Ways to Initialize an Empty Python Array

January 12, 2026 - Using np.empty() is the fastest way to create a Python array because it allocates the memory without setting any initial values. Choosing the right Python array method depends entirely on your specific use case. If you are just collecting a random set of US states or names, a standard Python list is almost always the right choice.

cs.du.edu › ~intropython › intro-to-programming › 2Dlist_define.html

Defining 2D lists - Introduction to Programming

Rather than focusing on 2D lists as a list of lists, another perspective is to think of it as a rectangular grid, each position having a row position and a column position. So to indicate a specific element, you give two index values. The first index gives the row and the second index gives the column. ... # Create an empty list temperature = [] # Four rows: for row in range(4): # Create an empty sub-list new_row = [] # Fill the row with three 0's for column in range(3): new_row.append(0) # Put the newly-created row into the outer list: temperature.append(new_row)

Thedeveloperblog

thedeveloperblog.com › 2d-list-python

Python 2D List Examples

We can access elements on each list with an index. With nested lists, we can create a lookup table or rectangular grid. Jagged row lengths, where each row has a different number of elements, are also allowed. General idea. We create an empty list and add empty lists to it with append().

geeksforgeeks.org › python-using-2d-arrays-lists-the-right-way

Python | Using 2D arrays/lists the right way - GeeksforGeeks

Manually initializing and populating a list without using any advanced features or constructs in Python is known as creating a 1D list using "Naive Methods". ... Here we are multiplying the number of rows by the empty list and hence the entire list is created with every element zero. ... Using 2D arrays/lists the right way involves understanding the structure, accessing elements, and efficiently manipulating data in a two-dimensional grid.

Published: June 20, 2024

blog.finxter.com › home › learn python blog › how to create a two dimensional array in python?

How To Create a Two Dimensional Array in Python? - Be on the Right Side of Change

June 11, 2022 - Here’s a diagrammatic representation ... If you want to create an empty 2D array without using any external libraries, you can use nested lists....

cs10.org › bjc-r › cur › programming › python › 2D_lists.html

2D Lists in Python - cs10.org

Now that you have some experience with lists in Python, try writing a function that takes a list of lists (2D) and returns all the items of each list concatenated together into one new list. See below for an example. Hint: To create an empty list, just set a variable equal to empty brackets, e.g.

note.nkmk.me › home › python

Initialize a List of Any Size with Specific Values in Python | note.nkmk.me

August 20, 2023 - A new list is created by repeating the elements of the original list a specified number of times. print([0, 1, 2] * 3) # [0, 1, 2, 0, 1, 2, 0, 1, 2] ... You can generate a list of sequential numbers with range(). ... Be cautious when initializing ...

geeksforgeeks.org › python › python-using-2d-arrays-lists-the-right-way

Using 2D arrays/lists in Python - GeeksforGeeks

Manually initializing and populating a list without using any advanced features or constructs in Python is known as creating a 1D list using "Naive Methods". ... Explanation: [0] * N creates a list of size N. ... Explanation: range(N) controls list length. A 2D list represents data in rows and columns.

Published: December 20, 2025