How to count frequency of non zero elements col wise

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Vishal Sharma
Vishal Sharma am 30 Jun. 2017
Kommentiert: Stephen23 am 30 Jun. 2017
I have a matrix
A = [
1 2 3 0 0;
2 2 0 2 1;
1 0 2 3 1]
I want to count column wise frequency of occurrence of all non zero numbers, i.e. 1, 2, 3 So as to get result in form of
First Col 1 (2) 2(1) 3(0)
Second Col 1(0) 2(2) 3(0)
Third Col 1(0) 2(1) 3(1)
Forth Col 1(0) 2(1) 3(1)
Fifth Col 1(2) 2(0) 3(0)

Akzeptierte Antwort

Stephen23
Stephen23 am 30 Jun. 2017
Bearbeitet: Stephen23 am 30 Jun. 2017
>> [N,C] = hist(A,0:3);
>> Z = N(C~=0,:).'
Z =
2 1 0
0 2 0
0 1 1
0 1 1
2 0 0
  2 Kommentare
Jan
Jan am 30 Jun. 2017
Bearbeitet: Jan am 30 Jun. 2017
What a pitty that hist is "not recommended" anymore. Do you knwo a method to process the matrix directly using the modern histcounts or histogram? I miss hist and histc.
But it is still working and nicer than the loop: +1
Stephen23
Stephen23 am 30 Jun. 2017
@Jan Simon: as I only have access to older MATLAB versions this topic has not yet come up for me... and why they needed to be replaced is not really very clear to me either.

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Jan
Jan am 30 Jun. 2017
Bearbeitet: Jan am 30 Jun. 2017
A = [1 2 3 0 0; ...
2 2 0 2 1; ...
1 0 2 3 1];
nCol = size(A, 2);
Edges = [unique(A(A ~= 0)); Inf];
Result = struct('N', cell(1, nCol));
for k = 1:nCol
Result(k).N = histcounts(A(:, k), Edges);
end
Or
Result = zeros(numel(Edges) - 1, nCol);
for k = 1:nCol
Result(:, k) = histcounts(A(:, k), Edges);
end

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