MATLAB: Vectorizing nested for loops

MATLABvectorization

How do I vectorize these for loops?

I am looking for the fastest implementation.

Thank you!

My current implementation is

d = zeros(N,N);
for i = 1:N
   for j = i:N
       d(i,j) = vecnorm( Phi(:,i) - Phi(:,j) ); 
   end
end
d = d + d';

Best Answer

A = magic(5) 
d = squareform(pdist(transpose(A))) % transpose to obtain vecnorm between columns

pdist and squareform are part of the Statistics Toolbox

Related Solutions

MATLAB: Error while calculating Cosine distance

To view answer:

ClientMean=....your matrix;
EvalSet=....your matrix;
Distance = CosineDistance(ClientMean, EvalSet)  % function call
celldisp(Distance)  % after the calling of the function

Just change yours to below:

function Distance = CosineDistance(ClientMean, EvalSet)  % function definition
        % Calculate Cosine Distance 
% 
%   Inputs:
%       ClientSet ---- c* dim matrix
%       EvalSet ---- n*dim matrix
%   Outputs:
%       Distance ---- c*n matrix
if ~exist('ClientMean','var')
    error('Input arguments error.');
end
if ~exist('EvalSet','var')
    error('Input arguments error.');
end
[c, d] = size(ClientMean);
[n, dim] = size(EvalSet);
if (d ~= dim)
    error('Dimensionality disagreement.');
end
Distance=cell(c,n);  % pre-allocate
ctr=1;
for i = 1 : c
    for j = 1 : n       
        norm_x = norm(ClientMean);
        norm_y = norm(EvalSet);
        Distance{ctr} = - (ClientMean(i,:)'*EvalSet(j,:))/(norm_x*norm_y);
        ctr=ctr+1;
    end
end
end

MATLAB: Following is the error while calculating cosine distance

cell is accessed using flower braces i.e {}. Replace Distance(ctr) with Distance{ctr}.

function Distance = CosineDistance(ClientMean, EvalSet)  % function definition
                        % Calculate Cosine Distance 
                % 
                %   Inputs:
                %       ClientSet ---- c* dim matrix
                %       EvalSet ---- n*dim matrix
                %   Outputs:
                %       Distance ---- c*n matrix
                if ~exist('ClientMean','var')
                    error('Input arguments error.');
                end
                if ~exist('EvalSet','var')
                    error('Input arguments error.');
                end
                [c, d] = size(ClientMean);
                [n, dim] = size(EvalSet);
                if (d ~= dim)
                    error('Dimensionality disagreement.');
                end
                Distance=cell(c,n);  % pre-allocate
                ctr=1;
                for i = 1 : c
                    for j = 1 : n       
                        norm_x = norm(ClientMean);
                        norm_y = norm(EvalSet);
                        Distance{ctr} = - (ClientMean(i,:)'*EvalSet(j,:))/(norm_x*norm_y);
                        ctr=ctr+1;
                    end
                end
  end

Best Answer

Related Solutions

MATLAB: Error while calculating Cosine distance

MATLAB: Following is the error while calculating cosine distance

Related Question