assign names in order?

Hello, I really want to know if there is any function or tool that I can use to give diferents names to diferents variables. I'm studying any features (like area, values of pixel, ecc..) of somes regions in an image, and then I want to save these, and here I have the problem. if I woul to save, for example: image 1: region1: num of object=...; area=...; centroid:... region2: num of object=...; area=... image 2:..... How can I "name", or "appoint" diferents features or image in order that I study it? Because I want to save all in a file without overwrite... I don't know if I explain it very well, but thank you

Answer 1

[Guillaume]

While you can generate variable names on the fly (using eval), it's not a good idea as it makes the code harder to understand, harder to debug, harder to check for syntax error and slower to execute.

In your case, what I would do is create structure arrays:

%hypothetical processing code
for imgindex = 1 : numimages
   img = loadimage(imgindex); %load an image
   numregions = regioncount(img); %get number of region
   for regionindex = 1 : numregions
      [area, centroid] = regionproperties(img, regionindex); %get property of region
      %HERE is where you store the result in structure arrays:
      imageprops(imgindex).region(regionindex).area  = area;
      imageprops(imgindex).region(regionindex).centroid = centroid;
   end
end

To access the area of the 5th region of the 3rd image:

area = imageprops(3).region(5).area;

[Maria]

ok, thanks. At the end, I did it in this way (the way you say). I was asking because I thought that saving in different variables would be more efficient, faster to execute, ecc... But you said the opposite, so thank you!! I have another question that maybe you can help me. I have 2 differents functions (created by me) with small differences, how can I see which one is faster? or more efficient? Maybe you know how thank you!!

[Guillaume]

As of R2014, the simplest way to compare functions is to use timeit. If you require more help start a new question.

[Maria]

Thank you!