title: Cross validation in r with categoical variable
body: <p>While I was trying to use cross-validation technique in R, I got this error which says</p>
  <blockquote>
  <p>Warning in train.default(x, y, weights = w, ...): cannnot compute class probabilities for regression</p>
  </blockquote>
  <blockquote>
  <p>Warning in nominalTrainWorkflow(x = x, y = y, wts = weights, info = trainInfo, :
  There were missing values in resampled performance measures.</p>
  </blockquote>
  <p>what am I supposed to do?</p>