/*
* 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.
*/
package org.apache.mahout.h2obindings.ops;
import org.apache.mahout.math.Vector;
import org.apache.mahout.h2obindings.H2OHelper;
import org.apache.mahout.h2obindings.drm.H2OBCast;
import org.apache.mahout.h2obindings.drm.H2ODrm;
import water.MRTask;
import water.fvec.Frame;
import water.fvec.Vec;
import water.fvec.Chunk;
import water.fvec.NewChunk;
/**
* Calculate Ax (where x is an in-core Vector)
*/
public class Ax {
/**
* Perform Ax operation with a DRM and an in-core Vector to create a new DRM.
*
* @param drmA DRM representing matrix A.
* @param x in-core Mahout Vector.
* @return new DRM containing Ax.
*/
public static H2ODrm exec(H2ODrm drmA, Vector x) {
Frame A = drmA.frame;
Vec keys = drmA.keys;
final H2OBCast<Vector> bx = new H2OBCast<Vector>(x);
// Ax is written into nc (single element, not array) with an MRTask on A,
// and therefore will be similarly partitioned as A.
//
// x.size() == A.numCols() == chks.length
Frame Ax = new MRTask() {
public void map(Chunk chks[], NewChunk nc) {
int chunkSize = chks[0].len();
Vector x = bx.value();
for (int r = 0; r < chunkSize; r++) {
double v = 0;
for (int c = 0; c < chks.length; c++) {
v += (chks[c].at0(r) * x.getQuick(c));
}
nc.addNum(v);
}
}
}.doAll(1, A).outputFrame(null, null);
// Carry forward labels of A blindly into ABt
return new H2ODrm(Ax, keys);
}
}