How do I shuffle a set of matrix to find the difference with another matrix?

Hi guys!

So my problem now is that I have two sets of data, both in the form of a matrix of 76x2000. Lets call them A and B.

For one of the matrix (lets say A), I want to relocate at random all the values in the matrix. And then, I will use that random matrix to subtract B and get a difference. I want to do this 1000 times (so basically (1000 different shuffled A) - B) and get an average value of the difference. Can someone please help me put this in a function?

Thank you very much.

Answer 1

[James Tursa]

A = whatever
B = whatever
m = 1000;  % Number of trials
n = numel(A);
C = zeros(1,n);
for k=1:m
    C = C + A(randperm(n));
end
result = reshape(C/m,size(A)) - B;

[Lakyn]

Hi! Thanks for your help.

When you say A = whatever B = whatever, can I just write like

A = []

B = []?

Thanks!

[James Tursa]

Sorry I wasn't clear. I am using your variable names. E.g.,

A = one of your 76x2000 matrices
B = your other 76x2000 matrix

[Lakyn]

no no its fine! thanks for the clarification. I know that its my two matrices, but I meant like in a function, the proper way to write it is

A = []

B = []

right? So this means like if I have 8 sets of A and B, I can use the same function for them all.

[Lakyn]

Hey!

Sorry, but ignore my previous question. I have fixed that. But regarding the code you wrote, I run the function and I get like 2000 columns worth of result in the command window, but how do I save it into the workplace section?

Thank you!

[James Tursa]

When calling a function that returns a variable:

myfunction(myinputs etc)  % <-- Splash the result to the display screen

x = myfunction(myinputs etc);  % <-- Save the result to variable x

Be sure to use the semi-colon at the end of the line to suppress the result splashing to the display screen.