CODEWITHSUNDEEP
matlabmatrixcell
lighting
lighting

Reputation: 400

Find the number of occurence of a matrix in cell

Let's assume that we have a matrix like this:

A = [1 2 3 4]

how can i find the number of occurrence of this matrix in a cell like this:

B{1,1} = {1, 7, 5, 7, 1, 2 ,3 ,4 ,9 ,4 ,6 ,1 ,2 ,3 ,7}
B{1,2} = {2, 3, 4, 5, 6, 0, 5, 1, 2, 3, 4, 5, 2, 1, 0}

Is it possible to find it without loops?

Thanks in advance!

Upvotes: 0

Views: 83

Answers (2)

Peter
Peter

Reputation: 14947

You can "abuse" strfind, assuming you can store B1 and B2 as matrices instead of cells. You can still use a cell for the outer layer, in order to support inputs of different lengths.

% Convert storage format
C{1} = cell2mat(B{1,1});
C{2} = cell2mat(B{1,2});

indices = cellfun(@(c) strfind(c,A), C, 'UniformOutput', false);

This finds all the starting indices in each array. If you just want the total number, count the occurrences:

occurrences = cellfun(@(c) length(strfind(c,A)));

Upvotes: 1

Valerio Raco
Valerio Raco

Reputation: 183

Solution with for loops: Without for loops is possible as well but it´s a readability nightmare. I would not suggest.

  numElA = numel(A);
    out    = zeros(size(B));
    for j = 1 : numel(B) % for every cell of B
        b = B{j}; % extract matrix
        for i = 1 : numel(b)-numElA % for every element of b (minus the size of A)
            out(j) = out(j) + all(cat(2,b{i+[0:numElA-1]})==A); % compare the two vectors (indexed b and a). If they are the same count them +1
        end
    end

update: this is the version without for loops

indA = 1:numel(A);
indB = cellfun(@(x) num2cell(bsxfun(@plus,(1:numel(x)-max(indA))',indA-1),2),B,'uniformoutput',false);
out  = cellfun(@sum,cellfun(@(MAT,IND) cellfun(@(ind) all(cat(2,MAT{ind})==A),IND),B,indB,'UniformOutput', false));

Upvotes: 2

Related Questions