average of matrix cells

what would be an efficient way to calculate the average of cells 1, cells2 , cells 3 from a matrix?

[Voss]

What is the expected result for the matrix shown?

[Ham Man]

Just three numbers which are the average of cells 1,average of cells 2,average of cells 3

[Voss]

By "cells 1", do you mean the elements that are 1? If so, their average will be 1.

Or by "cells 1", do you mean the elements around the outer edges of the matrix, which are labeled as 1 but actually contain other numbers?

I think a concrete example matrix and expected result would be very useful.

Answer 1

[Voss]

Here are a couple of guesses:

1.

M = ones(7);
M(2:end-1,2:end-1) = 2;
M(3:end-2,3:end-2) = 3;
M(4,4) = 4

M = 7×7

1 1 1 1 1 1 1 1 2 2 2 2 2 1 1 2 3 3 3 2 1 1 2 3 4 3 2 1 1 2 3 3 3 2 1 1 2 2 2 2 2 1 1 1 1 1 1 1 1

cells1avg = mean(M(M == 1))

cells1avg = 1

cells2avg = mean(M(M == 2))

cells2avg = 2

cells3avg = mean(M(M == 3))

cells3avg = 3

2.

labels = M

labels = 7×7

1 1 1 1 1 1 1 1 2 2 2 2 2 1 1 2 3 3 3 2 1 1 2 3 4 3 2 1 1 2 3 3 3 2 1 1 2 2 2 2 2 1 1 1 1 1 1 1 1

M = randi(10,7,7)

M = 7×7

4 4 7 1 1 6 9 4 10 2 1 5 1 6 4 10 2 8 6 7 5 1 5 2 10 6 8 9 4 8 10 3 3 9 8 5 6 5 9 10 8 10 10 3 6 7 10 6 4

cells1avg = mean(M(labels == 1))

cells1avg = 5.5833

cells2avg = mean(M(labels == 2))

cells2avg = 6.5000

cells3avg = mean(M(labels == 3))

cells3avg = 5

Answer 2

[Shubham]

Hi Ham,

To calculate the average of specific cells in a matrix in MATLAB, you can use the mean function along with indexing. Here's an example of how you can calculate the average of cells 1, 2, and 3 from a matrix:

% Create a sample matrix
matrix = [1 2 3; 4 5 6; 7 8 9];

% Calculate the average of cells 1, 2, and 3
average = mean(matrix(1:3));

% Display the result
disp(average);

In this example, the matrix is defined as a 3x3 matrix. By using indexing matrix(1:3), we select the first three elements from the matrix. Finally, the mean function calculates the average of those elements, and the result is displayed using disp.