title: Input matrix to opencv kmeans clustering
body: <p>This question is specific to opencv:
  The kmeans example given in the opencv documentation has a 2-channel matrix - one channel for each dimension of the feature vector. But, some of the other example seem to say that it should be a one channel matrix with features along the columns with one row for each sample. Which of these is right?</p>
  
  <p>if I have a 5 dimensional feature vector, what should be the input matrix that I use:
  This one:</p>
  
  <pre><code>cv::Mat inputSamples(numSamples, 1, CV32FC(numFeatures))
  </code></pre>
  
  <p>or this one:</p>
  
  <pre><code>cv::Mat inputSamples(numSamples, numFeatures, CV_32F)
  </code></pre>