In the previous article, we have discussed Python Program to Interchange Elements of First and Last Rows in Matrix
Given a matrix and the task is to get the sum of middle row elements and the middle column elements of a given matrix.
What is a matrix:
A matrix is a rectangular sequence of numbers divided into columns and rows. A matrix element or entry is a number that appears in a matrix.
Example:
Above is the matrix which contains 5 rows and 4 columns and having elements from 1 to 20.
In this order, the dimensions of a matrix indicate the number of rows and columns.
Here as there are 5 rows and 4 columns it is called a 5*4 matrix.
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Examples:
Example1:
Input:
Given Matrix : 4 2 0 4 2 3 5 6 9
Output:
The sum of middle row elements of the above given matrix = 9 The sum of middle column elements of the above given matrix = 10
Example2:
Input:
Given Matrix : 0 1 3 4 5 6 8 2 1
Output:
The sum of middle row elements of the above given matrix = 15 The sum of middle column elements of the above given matrix = 8
Program for Sum of Middle Row and Column in Matrix in Python
Below are the ways to get the sum of middle row elements and the middle column elements of a given matrix in python:
Method #1: Using For Loop (Static Input)
Approach:
- Give the matrix as static input and store it in a variable.
- Calculate the number of rows of the given matrix by calculating the length of the nested list using the len() function and store it in a variable mtrxrows.
- Calculate the number of columns of the given matrix by calculating the length of the first list in the nested list using the len() function and store it in a variable mtrxcolums.
- Take a variable to say middlrow_sum and initialize its value to 0.
- Take a variable to say middlcol_sum and initialize its value to 0.
- Loop till the given number of rows using the For loop.
- Inside the for loop, add mtrx[mtrxrows // 2][itr] to the above-initialized middlrow_sum where itr is the iterator value of the for loop.
- Print the sum of the middle row elements of the given matrix.
- Loop till the given number of rows using the For loop.
- Inside the for loop, add mtrx[itr][mtrxrows // 2] to the above-initialized middlcol_sum where itr is the iterator value of the for loop.
- Print the sum of the middle column elements of the given matrix.
- The Exit of the Program.
Below is the implementation:
# Give the matrix as static input and store it in a variable.
mtrx = [[4, 2, 0], [4, 2, 3], [5, 6, 9]]
# Calculate the number of rows of the given matrix by
# calculating the length of the nested list using the len() function
# and store it in a variable mtrxrows.
mtrxrows = len(mtrx)
# Calculate the number of columns of the given matrix by
# calculating the length of the first list in the nested list
# using the len() function and store it in a variable mtrxcols.
mtrxcols = len(mtrx[0])
# Take a variable to say middlrow_sum and initialize its value to 0.
middlrow_sum = 0
# Take a variable to say middlcol_sum and initialize its value to 0.
middlcol_sum = 0
# Loop till the given number of rows using the For loop.
for itr in range(mtrxrows):
# Inside the for loop, add mtrx[mtrxrows // 2][itr] to the above-initialized middlrow_sum
# where itr is the iterator value of the for loop.
middlrow_sum += mtrx[mtrxrows // 2][itr]
# Print the sum of the middle row elements of the given matrix.
print("The sum of middle row elements of the above given matrix = ",
middlrow_sum)
# Loop till the given number of rows using the For loop.
for itr in range(mtrxrows):
# Inside the for loop, add mtrx[itr][mtrxrows // 2] to the above-initialized middlcol_sum
# where itr is the iterator value of the for loop.
middlcol_sum += mtrx[itr][mtrxrows // 2]
# Print the sum of the middle column elements of the given matrix.
print("The sum of middle column elements of the above given matrix = ",
middlcol_sum)
Output:
The sum of middle row elements of the above given matrix = 9 The sum of middle column elements of the above given matrix = 10
Method #2: Using For loop (User Input)
Approach:
- Give the number of rows of the matrix as user input using the int(input()) function and store it in a variable.
- Give the number of columns of the matrix as user input using the int(input()) function and store it in another variable.
- Take a list and initialize it with an empty value using [] or list() to say gvnmatrix.
- Loop till the given number of rows using the For loop
- Inside the For loop, Give all the row elements of the given Matrix as a list using the list(),map(),int(),split() functions and store it in a variable.
- Add the above row elements list to gvnmatrix using the append() function.
- Take a variable to say middlrow_sum and initialize its value to 0.
- Take a variable to say middlcol_sum and initialize its value to 0.
- Loop till the given number of rows using the For loop.
- Inside the for loop, add mtrx[mtrxrows // 2][itr] to the above-initialized middlrow_sum where itr is the iterator value of the for loop.
- Print the sum of the middle row elements of the given matrix.
- Loop till the given number of rows using the For loop.
- Inside the for loop, add mtrx[itr][mtrxrows // 2] to the above-initialized middlcol_sum where itr is the iterator value of the for loop.
- Print the sum of the middle column elements of the given matrix.
- The Exit of the Program.
Below is the implementation:
# Give the number of rows of the matrix as user input using the int(input()) function
# and store it in a variable.
mtrxrows = int(input('Enter some random number of rows of the matrix = '))
# Give the number of columns of the matrix as user input using the int(input()) function
# and store it in another variable.
mtrxcols = int(input('Enter some random number of columns of the matrix = '))
# Take a list and initialize it with an empty value using [] or list() to say gvnmatrix.
mtrx = []
# Loop till the given number of rows using the For loop
for n in range(mtrxrows):
# Inside the For loop, Give all the row elements of the given Matrix as a list using
# the list(),map(),int(),split() functions and store it in a variable.
l = list(map(int, input(
'Enter {'+str(mtrxcols)+'} elements of row {'+str(n+1)+'} separated by spaces = ').split()))
# Add the above row elements list to gvnmatrix using the append() function.
mtrx.append(l)
# Take a variable to say middlrow_sum and initialize its value to 0.
middlrow_sum = 0
# Take a variable to say middlcol_sum and initialize its value to 0.
middlcol_sum = 0
# Loop till the given number of rows using the For loop.
for itr in range(mtrxrows):
# Inside the for loop, add mtrx[mtrxrows // 2][itr] to the above-initialized middlrow_sum
# where itr is the iterator value of the for loop.
middlrow_sum += mtrx[mtrxrows // 2][itr]
# Print the sum of the middle row elements of the given matrix.
print("The sum of middle row elements of the above given matrix = ",
middlrow_sum)
# Loop till the given number of rows using the For loop.
for itr in range(mtrxrows):
# Inside the for loop, add mtrx[itr][mtrxrows // 2] to the above-initialized middlcol_sum
# where itr is the iterator value of the for loop.
middlcol_sum += mtrx[itr][mtrxrows // 2]
# Print the sum of the middle column elements of the given matrix.
print("The sum of middle column elements of the above given matrix = ",
middlcol_sum)
Output:
Enter some random number of rows of the matrix = 3
Enter some random number of columns of the matrix = 3
Enter {3} elements of row {1} separated by spaces = 0 1 3
Enter {3} elements of row {2} separated by spaces = 4 5 6
Enter {3} elements of row {3} separated by spaces = 8 2 1
The sum of middle row elements of the above given matrix = 15
The sum of middle column elements of the above given matrix = 8
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