/*
* 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.h2obindings.drm.H2ODrm;
import water.MRTask;
import water.fvec.Frame;
import water.fvec.Vec;
import water.fvec.Chunk;
import water.fvec.NewChunk;
/**
* Calculate AB'
*/
public class ABt {
/**
* Calculate AB' on two DRMs to create a new DRM holding the result.
*
* @param drmA DRM representing matrix A
* @param drmB DRM representing matrix B
* @return new DRM containing AB'
*/
public static H2ODrm exec(H2ODrm drmA, H2ODrm drmB) {
Frame A = drmA.frame;
Vec keys = drmA.keys;
final Frame B = drmB.frame;
int ABt_cols = (int)B.numRows();
// ABt is written into ncs[] with an MRTask on A, and therefore will
// be similarly partitioned as A.
//
// chks.length == A.numCols() (== B.numCols())
// ncs.length == ABt_cols (B.numRows())
Frame ABt = new MRTask() {
public void map(Chunk chks[], NewChunk ncs[]) {
int chunkSize = chks[0].len();
Vec B_vecs[] = B.vecs();
for (int c = 0; c < ncs.length; c++) {
for (int r = 0; r < chunkSize; r++) {
double v = 0;
for (int i = 0; i < chks.length; i++) {
v += (chks[i].atd(r) * B_vecs[i].at(c));
}
ncs[c].addNum(v);
}
}
}
}.doAll(ABt_cols, A).outputFrame(null, null);
// Carry forward labels of A blindly into ABt
return new H2ODrm(ABt, keys);
}
}