private double[] initProbability() {
        double[] prob = new double[langlist.size()];
        if (priorMap != null) {
            for(int i=0;i<prob.length;++i) prob[i] = priorMap[i];
        } else {
            for(int i=0;i<prob.length;++i) prob[i] = 1.0 / langlist.size();
        }
        return prob;
    }