    001/*-
    002 * Copyright 2016 Diamond Light Source Ltd.
    003 *
    004 * All rights reserved. This program and the accompanying materials
    005 * are made available under the terms of the Eclipse Public License v1.0
    006 * which accompanies this distribution, and is available at
    007 * http://www.eclipse.org/legal/epl-v10.html
    008 */
    009
    010package org.eclipse.january.dataset;
    011
    012import java.util.List;
    013
    014/**
    015 * Class to run over a pair of datasets in parallel with NumPy broadcasting of second dataset
    016 */
    017public class BroadcastSingleIterator extends BroadcastSelfIterator {
    018        private int[] bShape;
    019        private int[] aStride;
    020        private int[] bStride;
    021
    022        final private int endrank;
    023
    024        private final int[] aDelta, bDelta;
    025        private final int aStep, bStep;
    026        private int aMax, bMax;
    027        private int aStart, bStart;
    028
    029        /**
    030         *
    031         * @param a
    032         * @param b
    033         */
    034        public BroadcastSingleIterator(Dataset a, Dataset b) {
    035                super(a, b);
    036
    037                int[] aShape = a.getShapeRef();
    038                maxShape = aShape;
    039                List<int[]> fullShapes = BroadcastUtils.broadcastShapesToMax(maxShape, b.getShapeRef());
    040                bShape = fullShapes.remove(0);
    041
    042                int rank = maxShape.length;
    043                endrank = rank - 1;
    044
    045                bDataset = b.reshape(bShape);
    046                int[] aOffset = new int[1];
    047                aStride = AbstractDataset.createStrides(aDataset, aOffset);
    048                bStride = BroadcastUtils.createBroadcastStrides(bDataset, maxShape);
    049
    050                pos = new int[rank];
    051                aDelta = new int[rank];
    052                aStep = aDataset.getElementsPerItem();
    053                bDelta = new int[rank];
    054                bStep = bDataset.getElementsPerItem();
    055                for (int j = endrank; j >= 0; j--) {
    056                        aDelta[j] = aStride[j] * aShape[j];
    057                        bDelta[j] = bStride[j] * bShape[j];
    058                }
    059                aStart = aOffset[0];
    060                bStart = bDataset.getOffset();
    061                aMax = endrank < 0 ? aStep + aStart: Integer.MIN_VALUE;
    062                bMax = endrank < 0 ? bStep + bStart: Integer.MIN_VALUE;
    063                reset();
    064        }
    065
    066        @Override
    067        public boolean hasNext() {
    068                int j = endrank;
    069                int oldB = bIndex;
    070                for (; j >= 0; j--) {
    071                        pos[j]++;
    072                        aIndex += aStride[j];
    073                        bIndex += bStride[j];
    074                        if (pos[j] >= maxShape[j]) {
    075                                pos[j] = 0;
    076                                aIndex -= aDelta[j]; // reset these dimensions
    077                                bIndex -= bDelta[j];
    078                        } else {
    079                                break;
    080                        }
    081                }
    082                if (j == -1) {
    083                        if (endrank >= 0) {
    084                                return false;
    085                        }
    086                        aIndex += aStep;
    087                        bIndex += bStep;
    088                }
    089
    090                if (aIndex == aMax || bIndex == bMax) {
    091                        return false;
    092                }
    093
    094                if (read) {
    095                        if (oldB != bIndex) {
    096                                if (asDouble) {
    097                                        bDouble = bDataset.getElementDoubleAbs(bIndex);
    098                                } else {
    099                                        bLong = bDataset.getElementLongAbs(bIndex);
    100                                }
    101                        }
    102                }
    103
    104                return true;
    105        }
    106
    107        /**
    108         * @return shape of first broadcasted dataset
    109         */
    110        public int[] getFirstShape() {
    111                return maxShape;
    112        }
    113
    114        /**
    115         * @return shape of second broadcasted dataset
    116         */
    117        public int[] getSecondShape() {
    118                return bShape;
    119        }
    120
    121        @Override
    122        public void reset() {
    123                for (int i = 0; i <= endrank; i++) {
    124                        pos[i] = 0;
    125                }
    126
    127                if (endrank >= 0) {
    128                        pos[endrank] = -1;
    129                        aIndex = aStart - aStride[endrank];
    130                        bIndex = bStart - bStride[endrank];
    131                } else {
    132                        aIndex = aStart - aStep;
    133                        bIndex = bStart - bStep;
    134                }
    135
    136                if (aIndex == 0 || bIndex == 0 || (endrank >= 0 && bStride[endrank] == 0)) { // for zero-ranked datasets or extended shape
    137                        if (read) {
    138                                storeCurrentValues();
    139                        }
    140                }
    141        }
    142}