MATLAB: How to find specific variables out of 2 different arrays

arraylogicvariablevector

I am given two different arrays. One is called wakeTimes and it is a 21 x 345 array. The other is, Section that is 345 x 1 containing the section numbers the subjects are in that are (0-6) I am trying to find the students that are in ONLY section 1 from the wake times. I understand you would have to use vector logic but how do i only pull out the information for those students.

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I created data and tested it with this code:

M = randi(9, 25, 6);                            % Wake Times
S = randi([0 6], 25, 1);                        % Sections
Out = M(S == 1, :);                             % Select Only Section ‘1’

It works.

Make the appropriate variable name substitutions to use it with your matrices and vector.

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MATLAB: Substracting a number from certain section of the array

Try this

A = [ 1.002 2.003 3.004 4.005 339.006 341.007 342.008 343.009 1.002 2.003 3.004 4.005];% your array 
A(A>300) = 360-A(A>300) % you want

MATLAB: How to manipulate arrays

Assigning one array to another is like assigning any other variable. Consider the B = A assignment here.

It looks as though you want to do a bubble sort, the simplest sorting algorithm. You’re close. This is how I would do it:

A = [2 1 4 3 6 5 8 7 10 9 12 11 14 13 16 15 18 17 20 19];
B = A;                                                      % Original Vector
swap = true;
while swap
    swap = false;
    for n = 1:length(A)-1
        if A(n) < A(n+1)
            tmp = A(n);
            A(n) = A(n+1);
            A(n+1) = tmp;
            swap = true;
        end
    end
end

The idea is to iterate the swapping loop until the ‘swap’ test is false ( i.e. no swap was made during a particular iteration of the vector ). Your loop sorts in descending order. You can add a counter to keep track of the number of swaps that were made.

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