public Map<Integer,Integer> getVertexMapping() {
        Map<Integer,Integer> vertexMapping = new HashMap<Integer,Integer>();
        for (int i = 0, j = 0; i < n1; ++i) {
            if (core1[i] != NULL_NODE) {
                vertexMapping.put(i, core1[i]);
            }
        }
        return vertexMapping;
    }
public Map < Integer , Integer > getVertexMapping ( ) { Map < Integer , Integer > vertexMapping = new HashMap < Integer , Integer > ( ) ; for ( int i = 0 , j = 0 ; i < n1 ; ++ i ) { if ( core1 [ i ] != NULL_NODE ) { vertexMapping . put ( i , core1 [ i ] ) ; } } return vertexMapping ; }
{@inheritDoc}