How can I calculate PCA?
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Thread: How can I calculate PCA?

  1. #1
    Join Date
    Feb 2013
    Posts
    21

    How can I calculate PCA?

    I am trying to use PCA, but it gives memory access violation error. Here is my sample code.

    Code:
    int main(...)
    {
    .................
    vector<float>input_array;
    
        for(i=0;i<number_of_lines;i++)
        {
            for(j=0;j<feature_vector_size;j++)
            {
                input_array.push_back(read_feature[i][j]);  
            }
    
            Mat input_feature_vector(input_array);
    
            Mat projection_result;
    
    
            PCA pca(input_feature_vector,Mat(),CV_PCA_DATA_AS_ROW, 0);/////error memory access
    
            pca.project(input_feature_vector,projection_result);
    
            for(k=0;k<feature_vector_size;k++)
            {
    
               fprintf(pca_output_file,"%lf ",projection_result.at <float>(k,0));
    
    
            }
    
                     fprintf(pca_output_file,"\n");
            input_array.clear ();
    
        }
    .............
    
    }
    Last edited by nihad; March 24th, 2013 at 12:05 AM.

  2. #2
    2kaud's Avatar
    2kaud is offline Super Moderator Power Poster
    Join Date
    Dec 2012
    Location
    England
    Posts
    5,872

    Re: How can I calculate PCA?

    In cases like this, there is a little known but extremely effective set of steps used by gurus to deal with the situation.

    The steps are
    1) Use the debugger to find the problem
    2) Find the problem using the debugger
    3) Follow all the steps
    All advice is offered in good faith only. All my code is tested (unless stated explicitly otherwise) with the latest version of Microsoft Visual Studio (using the supported features of the latest standard) and is offered as examples only - not as production quality. I cannot offer advice regarding any other c/c++ compiler/IDE or incompatibilities with VS. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain https://creativecommons.org/publicdomain/zero/1.0/ and can be used without reference or acknowledgement. Also note that I only provide advice and guidance via the forums - and not via private messages!

    C++17 Compiler: Microsoft VS2017 (15.5.0)

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