how to create histogram for each value of a matrix

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?

thanks

Answer 1

[Ruger28]

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
xlabel('Values');
ylabel('Percentage [%]');

[adi]

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!!