mean of a set of data

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joo
joo il 28 Nov 2012
if we have the mean of a set of numbers, we can find the standard deviation. is there a command in matlab, ie, a parameter to compare the data of a mean closed curve with the data of all the original closed curves. something like the satandard deviation for this case...
imagine i have
3 2 4
2 3 7
4 2 3
the mean
3
4
3
and then some parameter like standard deviation, that is not applicable for this case of course
thank you

Risposte (1)

Walter Roberson
Walter Roberson il 28 Nov 2012
M = mean(YourArray, 2); %calculate the means
T = repmat(M, 1, size(YourArray2)); %replicate the means
T < YourArray %compare the mean with all of the data
  9 Commenti
Image Analyst
Image Analyst il 29 Nov 2012
Joo, you need to explain this more completely from the start. It's like each time you add just another small but incomplete part of the puzzle. It's like you want an elephant detector, and then you ask us how to measure gray color, and not mention that you want to detect elephants. So we tell you only how to measure gray, and then you say that it doesn't work because it calls a wolf an elephant (but you don't tell us that fact - why it doesn't work). Well, if all you wanted was to measure gray, then that's what we gave you, and then of course it will also detect a wolf because it's gray too. Then you ask us to give you something that detect gray but no hair, and so we add a "hair detector" to tell wolves and elephants apart still without knowing you want an elephant detector. All we know is that you told us gray and no hair. But we may have to suggest more modifications when you come back and tell us that it's still not working but neglect to tell us that the reason it doesn't work is because it now classifies rhinoceroses as elephants. The point is that if you just tell us parts of the puzzle you will get only partial, sub-optimal answers.
First you just want the mean and standard deviation of an array. Then we learn that they numbers in it represent some kind of noisy samples of the boundary of circles. Well, okay we could then find the centroid and calculate the mean radius of the wiggly circles and the standard deviation of the radii. But I'm not even sure that's what you want or need because you haven't given us the full story. For example let's say you want to discriminate sickle cells from normal round red blood cells, and you think that the way to do that is to find boundary points and get the standard deviation of the center-to-boundary distance as you move around the boundary. Well, there's an easier way to do that (ask regionprops for the eccentricity) but we won't know to suggest that because you have not told us the real, final thing that you want to do or measure - you've only told us some algorithm that you think might be best. But it may not be the best way and you could take advantage of hundreds if not thousands of years of image processing experience in this community if you just told the community what you really want to do.
Walter Roberson
Walter Roberson il 29 Nov 2012
Heh. Mind you, I did suggest regionprops eccentricity earlier ;-)

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