MATLAB Answers

how to create histogram for each value of a matrix

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adi on 13 May 2020
Commented: adi on 14 May 2020
Hi all,
I have a 300X332 double matrix and i need to have an histogram of each value from the matrix in precentage. i'll explain by a simple example:
assume i have M=[1,1,2,3; 0,4,2,2; 1,1,1,1] iwant to have an histogram that will tell me how many times i have each value of the matrix out of all matrix veriables in precentage. for example the value of 1 will have a bin with height of 50%.
i used histogram func and can get only bins that are wider than only one value - bins of value 1 between 2 then 3 between 4 and so on..
later i need to extract the matrix values that correspond to 80%-90% of the whole matrix
how can i do it?


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Answers (1)

Ruger28 on 13 May 2020
Edited: Ruger28 on 13 May 2020
M=[1,1,2,3; 0,4,2,2; 1,1,1,1];
N = M(:); % make into vector
[SortedMat,I] = sort(N); % sort data
[UnVals,uIDX] = unique(SortedMat); % get unique values
P = histcounts(SortedMat); % get number of times the number appears
num_of_elems = numel(M); % get total number of values in matrix
PercentVals = P / num_of_elems; % divide to get percent of matrix
bar(UnVals,PercentVals); % plot
ylabel('Percentage [%]');

  1 Comment

adi on 14 May 2020
hi, i tried your code, but when i imply my code it doesnt work, p after the histcounts isnt the same length as UnVals. I did exactly the same as you did,just replaced M by Gmag of size 137X367.
i attached an image of my workspace.
what is wrong?
thank you!!

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