Loop for concentric squares

Question

hoennnoodle 2021-2-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/753919-loop-for-concentric-squares

编辑： Adam Danz 2021-2-23

I want to try and make a loop that makes concentric square matricies. Just as an example, I have my sample code here:

A = zeros(20)
%difference = 2
A(3:18,3:18) = 1
A(5:16,5:16) = 0
A(7:14, 7:14) = 1
A(9:12, 8:12) = 0

So I start with a matrix of height H and there's a height difference 'difference' between each matrix (in my example, it's 2). I'm not sure how I could use a 'for' loop to automatically do this since I'm not sure how to assign a name to each subsequent matrix in my code. Any help is appreciated.

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Answer 1

Adam Danz 2021-2-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/753919-loop-for-concentric-squares#answer_631264

编辑：Adam Danz 2021-2-23

在 MATLAB Online 中打开

Vectorized version,

sz = 20; % matrix size, square, positive integer

difference = 2; % width of bands, positive integer 1 <= x <= (sz/2)-1

% Create matrix

nestedMat = (sz-difference*2):-difference*2:0;

layers = arrayfun(@(m){padarray(ones(m),(sz-m)*[.5,.5])},nestedMat);

A = mod(sum(cat(3,layers{:}),3),2);

% Plot it

imagesc(A)

axis equal

Loop version,

sz = 20;         % matrix size, square, positive integer
difference = 2;  % width of bands, positive integer 1 <= x <= (sz/2)-1
% Create matrix
nestedMat = (sz-difference*2):-difference*2:0;
layers = zeros(sz);
for i = 1:numel(nestedMat)
    layers = layers + padarray(ones(nestedMat(i)), (sz-nestedMat(i))*[.5,.5]);
end
A = mod(layers,2);
% Plot it
imagesc(A)
axis equal