Improving my code - I'm trying to generate a checkerboard of size (222,786); length of each size 20. My code did work but I feel the logic can be improved. Kindly help.

Question

Bhargav Boddupalli 2018-2-18

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/383359-improving-my-code-i-m-trying-to-generate-a-checkerboard-of-size-222-786-length-of-each-size-20

编辑： John D'Errico 2018-2-18

% Channel number 90 to 875
chan = 1:1:786;
no_of_chan=length(chan);
% ffid 77 to 298
ffid = 1:1:222;
no_of_ffid=length(ffid);
% Pre-declaring 'checker' - it is two dimensional
checker=zeros(no_of_ffid,no_of_chan);
% Parameter to switch between positive and negative trains within if
% statement
anomaly=-1;
% 1 cell = 100 metres
dimension=20; 
% train is the size of one edge of one checker
train=ones(1,dimension);
for i=1:ceil((no_of_chan/dimension) - 1 )
      if anomaly==1
          train = [train ones(1,dimension)];
             anomaly=-1;
     else
         train = [train -1*ones(1,dimension)];
             anomaly=1;
     end 
end
for i=1:no_of_ffid
      if anomaly==1
          checker(i,:)=train(1:no_of_chan);
          if rem(i,dimension)==0
              anomaly=-1;
          end
      else 
          checker(i,:)=-1*train(1:no_of_chan);
          if rem(i,dimension)==0
              anomaly=1;
          end
      end
end
imshow(checker);

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Image Analyst 2018-2-18

Why not simply use the built-in checkerboard() function, in the Image Processing Toolbox?

Bhargav Boddupalli 2018-2-18

I tried it but I couldn't generate with required dimensions - 222x786

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Answer 1

John D'Errico 2018-2-18

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/383359-improving-my-code-i-m-trying-to-generate-a-checkerboard-of-size-222-786-length-of-each-size-20#answer_305763

编辑：John D'Errico 2018-2-18

在 MATLAB Online 中打开

Shiver. Yes, it can be improved. :) Honestly, what you have done is highly convoluted. That is not bad for someone learning to program. But you are thinking in terms of loops. You are growing arrays dynamically. There are branches and tests in your code when none need exist.

You want to create an array, of size 222x786. Alternating black and white squares, of size 20? The white squares will be 1, the black squares filled with -1?

rdim = 222;
cdim = 786;
squaresize = 20;
[rind,cind] = ndgrid(0:rdim-1,0:cdim-1);
rind = floor(rind/squaresize);
cind = floor(cind/squaresize);
checker = 1 - 2*mod(rind + cind,2);