public String getNodesAsString() {
		String s = "";
		for(int i = numSamples + 1; i >= 0; i--) {
			ArrayList<PHYNode> levelNodes = nodes.get(i);
			if(levelNodes != null) {
				for(PHYNode n : levelNodes) {
					if(n.isRoot()) continue;
					String tag = n.getSNVGroup().getTag();
					s += n.getNodeId() + "\t";
					s += tag + "\t";
					s += n.getCluster().getMembership().size() + "\t";
					double[] c = n.getCluster().getCentroid();
					DecimalFormat df = new DecimalFormat("#.##");
					int idx = 0;
					for(int j = 0; j < tag.length(); j++) {
						if(tag.charAt(j) == '1') {
							s += df.format(c[idx]) + "\t";
							idx++;
						} else {
							s += df.format(0) + "\t";
						}
					}
					s += "\n";
				}
			}
		}
		return s;
	}