SparseSimMatrix.java

package kb.howtokb.utils;

import gnu.trove.TLongFloatHashMap;

public class SparseSimMatrix {

	TLongFloatHashMap matrix;
	float threshold;

	public SparseSimMatrix(float thres) {
		matrix = new TLongFloatHashMap();
		this.threshold = thres;
	}

	public void set(int x, int y, float value) {
		if (value < threshold)
			return;
		long key = intpairToLong(x, y);
		matrix.put(key, value);
	}

	//Matrix is symmetric then only store the upper triangle part
	public float get(int x, int y) {
		if (x <=y )
			return matrix.get(intpairToLong(x, y));
		return matrix.get(intpairToLong(y, x));
	}

	private long intpairToLong(int l, int r) {
		return ((long) l << 32) + r;
		// return (long) (l << 32) | (r & 0XFFFFFFFFL);
	}

}