Comparing value in m x n matrices to find its index

Question

Tifani Utami 2016-4-28

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/281496-comparing-value-in-m-x-n-matrices-to-find-its-index

评论： Tifani Utami 2016-5-3

Hi, I have one set of data that I need to compare it with different size of data. So, as it stated in this code below, the threshold will be 3, 3.5, 4, 4.5 ..... I have to compare each threshold with all available data in variable GtrecMRCG2 then get its index. after all data compared, I need to check it with remaining threshold in variable thresholdVAR.

I wrote this based on my understanding. but it doesn't work because the dimension is mismatched. Thank you so much and big appreciation to those who want to give me advises. :)

threshold = 3;
thresholdVAR=[threshold 0 0 0 0 0 0 0 0];
GtrecMRCG2= [ 5 8 9 6 2 5 2 4 6 3 8 9 11];
for ii=1:9
    thresholdVAR(ii+1:end)= thresholdVAR(ii)+ 0.5;
  end
for idxm=1:length(thresholdVAR)
for idxn = 1:length(GtrecMRCG2)
idxalarmMRCG (1:length(thresholdVAR),1:length(GtrecMRCG2))= find(GtrecMRCG2(idxm,idxn)>=thresholdVAR(idxm,idxn));
end
end

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CS Researcher 2016-5-1

在 MATLAB Online 中打开

Not exactly sure what you are trying to achieve but you should see the line with the code:

find( thresholdVAR(idxm:sza(1),idxn:sza(2)) < GtrecMRCG2(1:sza(1),1:sza(2)));

Your thresholdVAR and GtrecMRCG2 are not 2D matrices. They both are 1D vectors.

Also, you don't need a loop to initialize the thresholdVAR. You can just do this:

thresholdVAR = 3:0.5:7;

Tifani Utami 2016-5-2

在 MATLAB Online 中打开

example first value of threshold. when threshold is 3, compare it with the value which in GtrecMRCG2 variable. find the index containing value that greater equal than GtrecMRCG2.

is_greater_equal will be [ 1 2 3 4 6 8 9 10 11 12 13]

then move to the next threshold which is 3.5

is_greater_equal = [ 1 2 3 4 6 8 9 10 11 12 13]

the process will keep going until all value which in GtrecMRCG2 compared with last threshold. my question is how to manipulate the output or to construct a new matrices as a result of comparison between two different matrices length.

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Answer 1

Ilham Hardy 2016-5-2

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/281496-comparing-value-in-m-x-n-matrices-to-find-its-index#answer_220355

在 MATLAB Online 中打开

Something like this?

thresholdVAR = 3:0.5:7;
GtrecMRCG2= [ 5 8 9 6 2 5 2 4 6 3 8 9 11];
% preallocate
DesMat = zeros(length(thresholdVAR),length(GtrecMRCG2));
for oneL = 1:length(thresholdVAR)
    [r,c,v] = find(GtrecMRCG2>thresholdVAR(oneL));
      DesMat(oneL,c) = GtrecMRCG2(c);
end