Method observe

src/com/winvector/util/CountMapV.java:30–37

Invariant: key set calls all keys ever observed (even those with net-zero count) @param key @param delta

(final T key, final int index, final double delta)

	 * @param delta
	 */
	public void observe(final T key, final int index, final double delta) {
		double[] v = counts.get(key);
		if(v==null) {
			v = new double[dim];
			counts.put(key,v);
		}
		v[index] += delta;
	}
	
	public boolean contains(final T key) {
		return counts.containsKey(key);