Home › Hendler Blog

no SPARQL RDF aggregate functions leading to other sorting routines

Thu, 09/06/2007 - 17:11 — jonathan
If SPARQL won't do it for me, I'll just have to do it myself... Well, it's easy in php:
foreach ($prepared_aggregates as $key => $row) {
    $count[$key]  = $row["count"];
}
array_multisort($count, SORT_NUMERIC,SORT_DESC, $prepared_aggregates);
 1
I started to write one in Java, but it was slower under Quercus because of type conversions

private Hashtable[] doOrderBy( 
            Hashtable[] results,
            String[] order_by,
            String[] sorting
            ){
        
        /**
         * a container for the return values
         * */
        //Hashtable<String,String>
        int resultlength = results.length;
        Hashtable[]  final_result = new Hashtable[resultlength] ; //new Hashtable<Integer, Hashtable<String,String>>();
        /**
         * a mapping for looking up keys of the provided results when the sorting is complete
         * */
        Hashtable<String,Integer> mapTable = new Hashtable<String,Integer>(); 
        
        /**
         * the array of strings for sorting
         * */
        ArrayList<String> sortingTable = new ArrayList<String>();
        
        /**
         * a container for the sort string
         * */
        String sortstring;
        
        //Enumeration<Integer> resultKeys = results.keys();
        //Enumeration<String> orders;
        String order_key;
        String order_value;
        Iterator it;
        
        Hashtable<String,String>  row = new Hashtable<String,String>();
        int rownumber=0;
        int or_num = order_by.length;
 
        
        //iterate over the results
        for(int j=0;j<resultlength;j++){
            sortstring = "";
            //rownumber = resultKeys.nextElement();
            row = results[j];
            //orders = order_by.keys();
            
            //iterate over the orders
            for(int i=0;i< or_num ; i++) {
                order_key = order_by[i];
                //order_key = orders.nextElement();
                //order_value = order_by.get(order_key);
                sortstring += row.get(order_key);
            }
            
            //get the string from the row and addit to the sortstring
            mapTable.put(sortstring,j);
            sortingTable.add(sortstring);
        }
        
        //sort the sortTable
        Collections.sort(sortingTable); //add MIXED ASC DESC
        it = sortingTable.iterator();
        //iterate the sort table
        //retrieve the result key from the sortable
        //get the hashtable result row from the results
        //place in the final results with the new sorted index
        rownumber = 0;
        String[] debugger = new String[results.length];
        while (it.hasNext()) {
            
           order_key =  (String)it.next();
           final_result[rownumber] = results[mapTable.get(order_key)];
          // debugger[rownumber] = order_key;
           rownumber++;
        }
        //return debugger;
        return final_result;
    }
 1
http://java.sun.com/docs/books/tutorial/collections/algorithms/index.html http://java.sun.com/javase/6/docs/api/java/util/Collections.html http://java.sun.com/javase/6/docs/api/java/util/Comparator.html