| /* |
| * 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.sysds.runtime.compress; |
| |
| import org.apache.sysds.runtime.compress.utils.DblArray; |
| import org.apache.sysds.runtime.data.SparseBlock; |
| import org.apache.sysds.runtime.matrix.data.MatrixBlock; |
| |
| /** |
| * Used to extract the values at certain indexes from each row in a sparse matrix |
| * |
| * Keeps returning all-zeros arrays until reaching the last possible index. The current compression algorithm treats the |
| * zero-value in a sparse matrix like any other value. |
| */ |
| public class ReaderColumnSelectionSparse extends ReaderColumnSelection { |
| |
| // reusable return |
| private DblArray reusableReturn; |
| private double[] reusableArr; |
| |
| // an empty array to return if the entire row was 0. |
| private DblArray empty = new DblArray(); |
| |
| private SparseBlock a; |
| |
| /** |
| * Reader of sparse matrix blocks for compression. |
| * |
| * This reader should not be used if the input data is not sparse |
| * |
| * @param data The transposed and sparse matrix |
| * @param colIndexes The column indexes to combine |
| */ |
| public ReaderColumnSelectionSparse(MatrixBlock data, int[] colIndexes) { |
| super(colIndexes, data.getNumRows()); |
| reusableArr = new double[colIndexes.length]; |
| reusableReturn = new DblArray(reusableArr); |
| a = data.getSparseBlock(); |
| } |
| |
| protected DblArray getNextRow() { |
| if(_lastRow == _numRows - 1) { |
| return null; |
| } |
| |
| _lastRow++; |
| |
| boolean zeroResult = true; |
| |
| if(a != null && !a.isEmpty(_lastRow)) { |
| |
| int apos = a.pos(_lastRow); |
| int alen = a.size(_lastRow) + apos; |
| int[] aix = a.indexes(_lastRow); |
| double[] avals = a.values(_lastRow); |
| int skip = 0; |
| int j = apos; |
| |
| while(skip < _colIndexes.length && j < alen) { |
| if(_colIndexes[skip] == aix[j]) { |
| reusableArr[skip++] = avals[j++]; |
| zeroResult = false; |
| } |
| else if(_colIndexes[skip] > aix[j]) { |
| j++; |
| } |
| else { |
| reusableArr[skip++] = 0; |
| } |
| |
| } |
| } |
| |
| return zeroResult ? empty : reusableReturn; |
| } |
| } |