How to set a moving window

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Lisa Fontana
Lisa Fontana on 15 Dec 2020
Edited: Lisa Fontana on 17 Dec 2020
Hi everyone. I need help with a moving window creation: I'm analyzing behavioral data collected from rats and I need to create a moving window showing how their psycometric curves change through each session. I don't need help with the psycometric curves creation, but I really don't know how to set the loop to create a moving window with a window of 50 and a step of 1...
I need to do this with a LOOP, so I don't want to use any function (like movmean or conv for example)
I really hope you can help me because this is driving me crazy

Accepted Answer

Image Analyst
Image Analyst on 15 Dec 2020
Why don't you want to use the built in function? Is it homework?
What do you want to do for elements 1-49? Or the final 49 elements? Do you want the window to shrink as your window would leave the array? Do you just want those places where the window fits complete in your array? Did you just try a simple for loop:
ratData = rand(1, 500); % Sample data
windowWidth = 50;
averagedData = zeros(1, length(ratData) - windowWidth);
for k = 1 : length(ratData) - windowWidth
averagedData(k) = mean(ratData(k:k+windowWidth-1));
end
plot(ratData, 'b-', 'LineWidth', 2);
hold on;
plot(averagedData, 'r-', 'LineWidth', 2);
grid on;
legend('Actual', 'Averaged');
msgbox('Done!');
  3 Comments
Image Analyst
Image Analyst on 17 Dec 2020
Maybe he doesn't know about the movmean() function so that's the reason why he suggested a loop. I see no real NEED for it to be a loop. Suggest the built-in movmean function to him. Or just go ahead and use it. I doubt he'd really care HOW you got it done.
Anyway, didn't my code do a manual 50 element moving mean? Not sure why it didn't meet your needs.
Lisa Fontana
Lisa Fontana on 17 Dec 2020
No sorry I haven't tried your code yet, I'll do it right now.
I just wanted to explain you exactly what I ment. So do you think your code will work for what I want?

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More Answers (1)

Steven Lord
Steven Lord on 15 Dec 2020
Use the value of the for loop variable as the index of the first element in the window. Add a quantity to get the index of the last element in the window. Use linear indexing to extract the elements in the window.
x = (1:10).^2
x = 1×10
1 4 9 16 25 36 49 64 81 100
y = x(4:7) % [16 25 36 49]
y = 1×4
16 25 36 49

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