How to convert a list to 2D array in Python : Know different Methods

A list is a data structure that allows you to store multiple values of objects in a single variable. Suppose you have a list and want to convert it into a 2D Array in python then how you will do it? In this entire tutorial, you will learn how to convert a list to a 2D array with various methods.

Create Sample List

Before going to the demonstration part first create a sample list that will be used to implement the various method.

Run the below lines of code to create a dummy list.

my_list = [10,20,30,40,50,60,70,80]

Methods to convert a list to a 2d array in python

Let’s know all the methods to convert the list to a 2D array.

Method 1: Convert a list to a 2d array in python using Numpy

In this method, I will use the numpy python package for the conversion of the list to a 2D array. Use the below lines of code to implement the conversion.

import numpy as np
my_list = [10,20,30,40,50,60,70,80]
final_list=[]
numpy_array = np.array(my_list).reshape(-1, 2)
list_2d = list(numpy_array)
for e in range(len(list_2d)):
  final_list.append(list(list_2d[e]))
print(final_list)

Here I have created an empty list that will store all the elements of the list converted in a numpy array as a list. You will get the output as below.

Output

conversion with numpy — conversion using numpy

Method 2: Convert list to 2d array python without numpy

The second method to convert a list to 2d without numpy is the use of the custom function. Here you will define some algo that will convert any list to a 2d array of any dimensions. Let’s create the function using the below lines of code.

def list_2d(list1,rows, columns):    
        result=[]               
        start = 0
        end = columns
        for i in range(rows): 
            result.append(list1[start:end])
            start +=columns
            end += columns
        return result

Let’s say the list is to be converted to 2 rows and 4 columns then I will add the below lines of code.

my_list = [10,20,30,40,50,60,70,80]
list_2d(my_list,2, 4)

Output

Conversion without numpy — Conversion without the use of numpy

In the same way, you can use 3 and 4 for 3 rows and 4 columns.

Conclusion

There can be many ways or methods to convert the list to a 2D array. Here I have written the best two methods to convert any list to a 2D array. One with NumPy and one without numpy or simply custom function.

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