queries/kmeans2.mrql

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

type point = < X: double, Y: double, Z: double >;

function distance ( x: point, y: point ): double {
   sqrt(pow(x.X-y.X,2)+pow(x.Y-y.Y,2)+pow(x.Z-y.Z,2))
};

aggregation new_centroid (
      \(p:(point,long),q:(point,long)):(point,long)
                .( < X: p#0.X+q#0.X, Y: p#0.Y+q#0.Y, Z: p#0.Z+q#0.Z >,
                   p#1+q#1),
      ( < X: 0.0 as double, Y: 0.0 as double, Z: 0.0 as double >,
        0 as long)
    ) : (point,long);

function centroid ( p: (point,long), default: point ): point {
   if p#1 = 0
      then default
      else < X: p#0.X/p#1, Y: p#0.Y/p#1, Z: p#0.Z/p#1 >
};

repeat centroids = select < X: random(1000)/100.0 as double,
       		   	    Y: random(1000)/100.0 as double,
			    Z: random(1000)/100.0 as double >
                     from x in 1..3
  step select ( centroid(new_centroid(select (p,1 as long) from p in s),k), true )
         from s in source(line,"queries/q.txt",",",type(<X:double,Y:double,Z:double>))
        group by k: (select c from c in centroids order by distance(c,s))[0]
  limit 10;