Outline: How To print a matrix in Python
numpy. array()method, or,numpy.matrixclass, or,- a list comprehension +
join()method join() + map()methods
Table of Contents
❖ Overview
A matrix is a two-dimensional data structure consisting of elements arranged in rows and columns. For example:
The above figure represents a 4×3 matrix since it has four rows and three columns.
Now that you know what a matrix is let us dive into the mission-critical question –
Problem Statement: Given a matrix as an input, how will you print and display it as an output in Python?
You might be wondering – “Can’t I simply print the matrix by storing it in a variable?”🤔 Unfortunately, it won’t print the input matrix. Instead, it will generate a list of lists, as shown below.
Print Matrix in Python
❖ Method 1: Using The NumPy Library
Python comes with a multitude of extremely powerful libraries which allow you to work with huge amounts of data with ease.
NumPy is a library in Python that is used for scientific computing and supports powerful functions to deal with N-dimensional array objects. It also provides us with functions for working in the domains of linear algebra, fourier transform, and matrices.
📓 Note: You need to install NumPy before you can use it. You can install it using –
| pip install numpy |
Let’s have a look at the different ways to create and print a matrix in Python using NumPy.
1️⃣ Using numpy.array()
The array() method of the NumPy library allows you to create and print a matrix object.
Example:
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import numpy as np arr = np.array([[0, 1, 4, 2, 3], [4, 2, 0, 1, 5], [2, 2, 1, 0, 3], [3, 4, 5, 3, 0]]) print(arr) |
Output:
[[0 1 4 2 3]
[4 2 0 1 5]
[2 2 1 0 3]
[3 4 5 3 0]]
2️⃣ Using numpy.matrix()
The numpy.matrix() class returns a matrix from an array-like object or a string of data.
Syntax:
| numpy.matrix(data, dtype = None) |
Example:
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import numpy as np arr = np.matrix([[0, 1, 4, 2, 3], [4, 2, 0, 1, 5], [2, 2, 1, 0, 3], [3, 4, 5, 3, 0]]) print(arr) |
Output:
[[0 1 4 2 3]
[4 2 0 1 5]
[2 2 1 0 3]
[3 4 5 3 0]]
⚠️Caution: It is not recommended to use this class anymore. Instead, you should opt for regular arrays. The class may be removed/deprecated in the future.
✨ TRIVIA
❖ Method 2: Using List Comprehension and join
✏️ In simple words, a list comprehension is a crisp and compact way of creating Python lists.
Syntax: [expression for item in iterable if condition == True]
Example:
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li = [i for i in range(1, 6)] print(li) # [1, 2, 3, 4, 5] |
✏️ join() is a function in Python that takes the items of an iterable and combines them into a single string.
Example:
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li = ["Java",'2','Blog'] print(''.join(li)) # Java2Blog |
Thus, you can leverage the functionality of a list comprehension along with the join method to print a matrix.
Example:
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arr = [[0, 1, 4, 2, 3], [4, 2, 0, 1, 5], [2, 2, 1, 0, 3], [3, 4, 5, 3, 0]] x = '\n'.join([''.join(['{:4}'.format(item) for item in row]) for row in arr]) print(x) |
Output:
0 1 4 2 3
4 2 0 1 5
2 2 1 0 3
3 4 5 3 0
You can also use a nested for loop to replicate the above concept.
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arr = [[0, 1, 4, 2, 3], [4, 2, 0, 1, 5], [2, 2, 1, 0, 3], [3, 4, 5, 3, 0]] for row in arr: for val in row: print(val, end=" ") print() |
But, the above code will result in 24 print statements as opposed to a single print statement in case of the list comprehension.
❖ Method 3: Using join()+map()
✏️ map( ) is an inbuilt method in Python that takes a function and an iterable as an input. It then executes the function by passing the iterable as an input to the function.
Syntax:
map(function, iterables) |
Example:
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arr = [[0, 1, 4, 2, 3], [4, 2, 0, 1, 5], [2, 2, 1, 0, 3], [3, 4, 5, 3, 0]] for i in arr: print('\t'.join(map(str, i))) |
Output:
0 1 4 2 3
4 2 0 1 5
2 2 1 0 3
3 4 5 3 0
Explanation:
- the for loop allows you to iterate through each individual array/row within the matrix.
map(str, i)converts all the items within each row to a string and then,'\t'.joincombines the individual items in a single string, and then each row gets printed one by one.
Conclusion
Thus, this article unveiled numerous methods to print a matrix in Python. The simplest and the most effective way to print a matrix in Python is undoubtedly the numpy.array() method as it takes care of all arrangements and dimensions without any interference for the user.
That’s all about how to print a matrix in Python.
Read here: [Fixed] ModuleNotFoundError: No module named ‘numpy’
With that, we come to the end of this tutorial. Please subscribe and stay tuned for more interesting discussions in the future. Happy coding! 📚
That’s all about how to print matrix in Python.
