Using find in a for loop error

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Serena Campbell 2018-2-12

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https://ww2.mathworks.cn/matlabcentral/answers/382202-using-find-in-a-for-loop-error

回答： Serena Campbell 2018-2-12

I have a large matrix with values of "period" p - I am testing this part of my code where I find what row p belongs to in order to access the corresponding row later in my code. However for some reason this will only run three times (so until cct=3) before i get the error: Assignment has more non-singleton rhs dimensions than non-singleton subscripts; error position1(cct,1)=find(p==pp)

*
p=AAA(1:end-1,1); %%%returns 10000x1 matrix of values 0 to 1 in 0.001 steps 
cct=1;
for pp =0.1:0.1:0.5;
      position1(cct,1)=find(p==pp);
      position2=position1(cct,1);
      valuep=p(position2,1); %%%to check it is the correct value
      cct=cct+1;
end*

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Serena Campbell 2018-2-12

编辑：Serena Campbell 2018-2-12

在 MATLAB Online 中打开

image.png

So - I put the output into a cell and a strange thing happens - it always skips the third value (no matter what the value is!) and continues nicely after? (see attached output)

p=AAA(1:end-1,1);
cct=1;
for pp =0.4:0.1:1;
      test(cct,1)=cct;
      valuepp(cct,1)=pp;
      x{cct,1}=find(p==pp);
  %     
      cct=cct+1;
end

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Answer 1

Matt J 2018-2-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/382202-using-find-in-a-for-loop-error#answer_304743

编辑：Matt J 2018-2-12

在 MATLAB Online 中打开

You would need to give us AAA in a .mat file to be certain. Most likely, however, pp is not close enough to 0.6 (due to floating point error) to match a value in AAA. Use a tolerance:

x{cct,1}=find(abs(p-pp)<smallnumber);