Storing values in an array

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NC 2018-6-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/406409-storing-values-in-an-array

评论： NC 2018-6-20

I want to calculate the distance to each pixel from the center pixel and sort the highest 4 values. I used the following code for that. But it gives the error "Subscript indices must either be real positive integers or logicals". How to solve it?

 totalVal = 0; 
 for h = 1 : H
    for w = 1:W
         %value = pdist2([cen h],[cen w],'euclidean');
         value(h,w) = sqrt((cen-h)^2 + (cen-w)^2); 
          end
end
 f3Row = reshape(value, 1, []); 
 [sortedDist, sortedInds] = sort(f3Row,'descend');
 highestDist = (sortedDist(1:4));
for num = 1:n
    totalVal = totalVal+highestDist(num);
end
 f3 = totalVal; 
 fprintf('Feature 03 : ');
 disp(f3);

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Jan 2018-6-19

Please post the error message. It is much easier to fix an error than to guess, what the error is.

NC 2018-6-20

Question was edited with the error message.

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采纳的回答

Walter Roberson 2018-6-20

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/406409-storing-values-in-an-array#answer_325382

在 MATLAB Online 中打开

centy = H/2;
centx = W/2;
[Hg, Wg] = ndgrid(1:H, 1:W);
value = sqrt((Hg - centy).^2 + (Wg - centx).^2);
sortedDist = sort(value(:), 'descend');
f3 = sum(sortedDist(1:4));

However, you can predict this value without doing any of this. The value will always be 4 * sqrt(H/2^2 + W/2)^2

Perhaps you are only to consider pixels that meet some particular condition, like belonging to a non-square ROI? And perhaps the center point is not the center of the image but is instead the centroid of the non-square ROI ?