com.ibm.bi.dml.runtime.instructions.spark.functions.ExtractGroupNWeights.java Source code

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/**
 * (C) Copyright IBM Corp. 2010, 2015
 *
 * Licensed 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.
 * 
*/

package com.ibm.bi.dml.runtime.instructions.spark.functions;

import java.util.ArrayList;

import org.apache.spark.api.java.function.PairFlatMapFunction;

import scala.Tuple2;

import com.ibm.bi.dml.runtime.matrix.data.IJV;
import com.ibm.bi.dml.runtime.matrix.data.MatrixBlock;
import com.ibm.bi.dml.runtime.matrix.data.MatrixIndexes;
import com.ibm.bi.dml.runtime.matrix.data.SparseRowsIterator;
import com.ibm.bi.dml.runtime.matrix.data.WeightedCell;
import com.ibm.bi.dml.runtime.util.UtilFunctions;

public class ExtractGroupNWeights implements
        PairFlatMapFunction<Tuple2<MatrixIndexes, Tuple2<Iterable<Tuple2<MatrixBlock, MatrixBlock>>, Iterable<MatrixBlock>>>, Long, WeightedCell> {

    private static final long serialVersionUID = -188180042997588072L;

    @Override
    public Iterable<Tuple2<Long, WeightedCell>> call(
            Tuple2<MatrixIndexes, Tuple2<Iterable<Tuple2<MatrixBlock, MatrixBlock>>, Iterable<MatrixBlock>>> arg)
            throws Exception {
        MatrixBlock group = null;
        MatrixBlock target = null;
        for (Tuple2<MatrixBlock, MatrixBlock> kv : arg._2._1) {
            if (group == null) {
                group = kv._1;
                target = kv._2;
            } else {
                throw new Exception("More than 1 block with same MatrixIndexes");
            }
        }
        MatrixBlock weight = null;
        for (MatrixBlock blk : arg._2._2) {
            if (weight == null) {
                weight = blk;
            } else {
                throw new Exception("More than 1 block with same MatrixIndexes");
            }
        }

        ArrayList<Double> groupIDs = getColumn(group);
        ArrayList<Double> values = getColumn(target);
        ArrayList<Double> w = getColumn(weight);
        ArrayList<Tuple2<Long, WeightedCell>> groupValuePairs = new ArrayList<Tuple2<Long, WeightedCell>>();

        if (groupIDs != null) {
            if (groupIDs.size() != values.size() || groupIDs.size() != w.size()) {
                throw new Exception("The blocksize for group, weight and target block are mismatched: "
                        + groupIDs.size() + " != " + values.size() + " || " + groupIDs.size() + " != " + w.size());
            }
            for (int i = 0; i < groupIDs.size(); i++) {
                WeightedCell weightedCell = new WeightedCell();
                try {
                    weightedCell.setValue(values.get(i));
                } catch (Exception e) {
                    weightedCell.setValue(0);
                }
                try {
                    weightedCell.setWeight(w.get(i));
                } catch (Exception e) {
                    weightedCell.setValue(1);
                }
                long groupVal = UtilFunctions.toLong(groupIDs.get(i));
                if (groupVal < 1) {
                    throw new Exception(
                            "Expected group values to be greater than equal to 1 but found " + groupVal);
                }
                groupValuePairs.add(new Tuple2<Long, WeightedCell>(groupVal, weightedCell));
            }
        } else {
            throw new Exception("group ids block shouldn't be empty");
        }

        return groupValuePairs;
    }

    public ArrayList<Double> getColumn(MatrixBlock blk) throws Exception {
        ArrayList<Double> retVal = new ArrayList<Double>();
        if (blk != null) {
            if (blk.isInSparseFormat()) {
                SparseRowsIterator iter = blk.getSparseRowsIterator();
                while (iter.hasNext()) {
                    IJV cell = iter.next();
                    retVal.add(cell.v);
                }
            } else {
                double[] valuesInBlock = blk.getDenseArray();
                for (int i = 0; i < valuesInBlock.length; i++) {
                    retVal.add(valuesInBlock[i]);
                }
            }
        }
        return retVal;
    }

}