Add two matrices using Python program

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In this program, you will learn to add two matrices using nested loops and next list comprehension, and display them.

To understand this example, you should understand the followingPython programmingTopic:

• Python for loop

• Python list
  

In Python, we can implement matrices as nested lists (lists within lists). We can consider each element as a row of the matrix.

For example, X = [[1, 2], [4, 5], [3, 6]] will represent a3x2Matrix. The first row can be chosen as X[0], and the element in the first row and first column can be chosen as X[0][0].

We can perform matrix addition in various ways in Python. Here are some examples.

Source code: Matrix addition using nested loops

# Program to add two matrices using nested loops
X = [[12,7,3],
　　　　[4　,5,6],
　　　　[7　,8,9]]
Y = [[5,8,1],
　　　　[6,7,3],
　　　　[4,5,9]]
result = [[0,0,0],
　　　　　　　　　[0,0,0],
　　　　　　　　　[0,0,0]]
# Traverse rows
for i in range(len(X)):
　　　# Iterate through columns
　　　for j in range(len(X[0])):
　　　　　　　result[i][j] = X[i][j]　+　Y[i][j]
for r in result:
　　　print(r)

Output result

[17,　15,　4]
[10,　12,　9]
[11,　13,　18]

In this program, we use nested for loops to traverse each row and column. At each point, we add the corresponding elements from the two matrices and store them in the result.

Source code: Matrix addition using nested list comprehension

# Program to add two matrices using list comprehension
X = [[12,7,3],
　　　　[4　,5,6],
　　　　[7　,8,9]]
Y = [[5,8,1],
　　　　[6,7,3],
　　　　[4,5,9]]
result = [[X[i][j]　+　Y[i][j] for j in range(len(X[0])) for i in range(len(X))]
for r in result:
　　　print(r)

The output of the program is the same as the one above. We use nested list comprehension to traverse each element in the matrix.

List comprehension allows us to write concise code, we must try to use them frequently in Python. They are very helpful.

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