Initialization of Y

  def initializeToCrfPotentials = {
      for (tweetIdx <- 0 until _Y.size) {
        for (tokenIdx <- 0 until _Y(tweetIdx).size) {
            for (labelIdx <- 0 until _Y(tweetIdx)(tokenIdx).size) {
                // Note: the +1 in token index is because of the <S> token at the beginning
                // of the CRF potentials.
                logger.info(tweetIdx + " " + tokenIdx + " " + labelIdx)
                _Y(tweetIdx)(tokenIdx)(labelIdx) = _crfPotentials(tweetIdx)(tokenIdx + 1)(labelIdx)
            }
        }
      }
  }