title: Predicting text data labels in test data set with Weka?
body: <p>I am using the Weka gui to train a SVM classifier (using libSVM) on a dataset.  The data in the .arff file is </p>
  
  <pre><code>@relation Expandtext
  
  @attribute message string 
  @attribute Class {positive, negative, objective}
  
  @data
  </code></pre>
  
  <p>I turn it into a bag of words with String-to-Word Vector, run SVM and get a decent classification rate.  Now I have my test data I want to predict their labels which I do not know.  Again it's header information is the same but for every class it is labeled with a question mark (?) ie</p>
  
  <pre><code>'Musical awareness: Great Big Beautiful Tomorrow has an ending\u002c Now is the time does not', ?
  </code></pre>
  
  <p>Again I pre-processed it, string-to-word-vector, class is in the same position as the training data.  </p>
  
  <p>I go to the "classify" menu, load up my trained SVM model, select "supplied test data", load in the test data and right click on the model saying "Re-evaluate model on current test set" but it gives me the error that test and train are not compatible.  I am not sure why.</p>
  
  <p>Am I going about this the wrong way to label the test data?  What am I doing wrong?</p>