CODEWITHSUNDEEP
matlabperformanceoptimizationcountconditional-statements
Tony Chivers
Tony Chivers

Reputation: 191

Counting values that meet a condition

I am trying to count the number of times a value in a column vector is greater than 0.5. The code below gets me where I need to be but I am wondering is this the most efficient way to do this. 

n = 500
AA = rand(n,1);
for i = 1:n
    if abs(AA(i))>0.5
      BB(i)=1;
    else
      BB(i)=0;
    end
end
sBB = sum(BB);
SD = sBB/n;

Upvotes: 0

Views: 393

Answers (1)

Dev-iL
Dev-iL

Reputation: 24169

This task can benefit from vectorization:

n = 500
AA = rand(n,1); % You used vectorization already (!) and not create each entry separately...
BB = AA>0.5;    % Results in a vector of logicals which signifies where the condition was met
SD = sum(BB)/n; % Can also be `nnz(BB)/n` or `mean(BB)`

Upvotes: 2

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