title: From confusion matrix to ROC graph
body: <p>i recently implemented a Bag of Words categorization algorithm based on the one described in <a href="http://217.109.185.161/layout/set/print/content/download/20785/148346/file/2004_010.pdf" rel="nofollow">this paper</a>.</p>
  
  <p>All works well, but i'd like to measure accuracies of the classifiers using ROC curves or, perhaps, precision-recall graphs.</p>
  
  <p>I can easily get the confusion matrix for each of the classifiers but i don't know what parameter i should change to get more points and actually plot the curves.</p>
  
  <p>Could someone please explain this to me?</p>