How to save logical arrays generated by for loops as matrices

Goal: to compare each value from a matrix to an index ranging from 0-4 in increments of 1, saving the results as a matrix.

Please see the sample code below: this produces the answers I want as 5 logical arrays, but the last one is the only one that is saved. I would like to save all 5 logical arrays as either a single matrix or as individual matrices. This is a simplified test run--ultimately, I will use increments of .01 and perform other calculations on each of the 400 matrices produced. Given this, should I save the arrays as a single matrix or as individual matrices for best practices with memory?

test = [1 2 3 4; 2 1 3 4; 3 1 2 4]

inc = zeros(3,4)                             
for index = 0:1:4
    inc = test >= index
end

*Please note: Based on (https://www.mathworks.com/videos/storing-data-in-a-matrix-from-a-loop-97493.html) I have tried writing the last line as:

inc(i) = test >= index

This returns the error "Array indices must be positive integers or logical values."

Thank you in advance!

Answer 1

[Walter Roberson]

test = [1 2 3 4; 2 1 3 4; 3 1 2 4];
inc = zeros(size(test,1),size(test,2),5);                             
for index = 0:1:4
    inc(:,:,index+1) = test >= index;
end

inc is now a 3 x 4 x 5 matrix with the third dimension corresponding to the different index values.

You can also skip the looping and do

test = [1 2 3 4; 2 1 3 4; 3 1 2 4];
inc = test >= reshape(0:1:4, 1, 1, []);

Requires R2016b or later.

[May_the_degrees_of_freedom_be_with_you]

Thank you so much for the quick response! Never would have thought to add a third dimension for the index values. Worked perfectly.