public double[] convertTweetToFeatures(String line) {
		double frequency[] = new double[featureSets.size()];
		int j, k;
		line = line.toLowerCase();
		for (j = 0; j < featureSets.size(); j++) 
		{
			for (k = 0; k < featureSets.get(j).size(); k++) 
			{
				frequency[j] += StringUtils.countMatches(line, (featureSets.get(j)).get(k));
			}
		}

		return frequency;
	}