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how to save variables to an array using a for loop?

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Debby Amaya
Debby Amaya on 29 Jun 2017
Edited: Jan on 30 Jun 2017
If I have m1 = 12, m2 = 34, m3 = 12, m4 = 45 how can I save it in the form of y = [m1, m2, m3, m4] using a for loop? kind of like.. for i = 2:6 y = ?.... Thanks
  3 Comments
Stephen
Stephen on 30 Jun 2017
"I calculated the mean pixel's value for several different images using MATlab, that's how I ended up with different variables"
So the best and simplest solution is to put that data into one variable when you make those calculations. That is what any experienced user would do, and you can do that too.
Presumably you perform those calculations in a loop: in that case you can simply preallocate the output matrix and use indexing inside the loop to allocate the calculated values. Simple, fast, efficient, neat, easy to understand... there is no reason why you cannot write good code now.

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Answers (2)


Jan
Jan on 30 Jun 2017
Edited: Jan on 30 Jun 2017
As suggested above: The best idea is not to create the variables in this way at all. Hiding an index in the name of the variable is a bad idea.
But if you have these names already and cannot change the code, which creates them - what's wrong with:
y = [m1, m2, m3, m4]
? Is the number of variables unknown? Do the variables come from an imported MAT file? Then this would help:
Data = load('File.mat');
C = struct2cell(Data);
M = cat(2, C{:});
Nevertheless, the main goal is to avoid the creation of such variables from the beginning.

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