content: // ===============================================================================
  // Authors: AFRL/RQQD
  // Organization: Air Force Research Laboratory, Aerospace Systems Directorate, Power and Control Division
  // 
  // Copyright (c) 2017 Government of the United State of America, as represented by
  // the Secretary of the Air Force.  No copyright is claimed in the United States under
  // Title 17, U.S. Code.  All Other Rights Reserved.
  // ===============================================================================
  
  /*
   * GRAL: GRAphing Library for Java(R)
   *
   * (C) Copyright 2009-2013 Erich Seifert <dev[at]erichseifert.de>,
   * Michael Seifert <mseifert[at]error-reports.org>
   *
   * This file is part of GRAL.
   *
   * GRAL is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * GRAL is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with GRAL.  If not, see <http://www.gnu.org/licenses/>.
   */
  package de.erichseifert.gral.data.filters;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.util.Arrays;
  
  import de.erichseifert.gral.data.Column;
  import de.erichseifert.gral.data.DataAccessor;
  import de.erichseifert.gral.data.DataSource;
  import de.erichseifert.gral.data.DataTable;
  import de.erichseifert.gral.data.Row;
  
  /**
   * Filter to change the size of equally spaced data sources. All columns of the
   * data sources must be numeric, otherwise an {@code IllegalArgumentException}
   * will be thrown. The values of the scaled result are created by averaging.
   */
  public class Resize extends Filter {
  	/** Version id for serialization. */
  	private static final long serialVersionUID = -5601162872352170735L;
  
  	/** Number of columns. */
  	private final int cols;
  	/** Number of rows. */
  	private final int rows;
  
  	/**
  	 * Initializes a new data source from an original data source and a
  	 * specified number of rows and columns.
  	 * @param data Original data source.
  	 * @param cols Number of columns for new data source.
  	 * @param rows Number of rows for new data source.
  	 */
  	public Resize(DataSource data, int cols, int rows) {
  		super(data, Mode.ZERO);
  		this.cols = cols;
  		this.rows = rows;
  		filter();
  	}
  
  	@Override
  	public int getColumnCount() {
  		if (cols <= 0) {
  			return super.getColumnCount();
  		}
  		return cols;
  	}
  
  	@Override
  	public int getRowCount() {
  		if (rows <= 0) {
  			return super.getRowCount();
  		}
  		return rows;
  	}
  
  	@Override
  	public Comparable<?> get(int col, int row) {
  		if ((cols <= 0 || cols == getOriginal().getColumnCount()) &&
  			(rows <= 0 || rows == getOriginal().getRowCount())) {
  			return getOriginal(col, row);
  		}
  		return super.get(col, row);
  	}
  
  	@SuppressWarnings({ "unchecked", "rawtypes" })
  	@Override
  	protected void filter() {
  		clear();
  		DataSource original = getOriginal();
  		if ((getRowCount() == original.getRowCount())
  				&& (getColumnCount() == original.getColumnCount())) {
  			return;
  		}
  
  		DataSource data = original;
  		if (getRowCount() != original.getRowCount()) {
  			Class[] dataTypes = new Class[original.getColumnCount()];
  			Arrays.fill(dataTypes, Double.class);
  			DataTable avgRows = new DataTable(dataTypes);
  			fillWithEmptyRows(avgRows, getRowCount());
  
  			double step = original.getRowCount() / (double) getRowCount();
  			for (int colIndex = 0; colIndex < original.getColumnCount(); colIndex++) {
  				Column colData = original.getColumn(colIndex);
  				for (int rowIndex = 0; rowIndex < getRowCount(); rowIndex++) {
  					double start = rowIndex*step;
  					double end   = (rowIndex + 1)*step;
  					avgRows.set(colIndex, rowIndex,
  							average(colData, start, end));
  				}
  			}
  			data = avgRows;
  		}
  		if (getColumnCount() != original.getColumnCount()) {
  			Class[] dataTypes = new Class[getColumnCount()];
  			Arrays.fill(dataTypes, Double.class);
  			DataTable avgCols = new DataTable(dataTypes);
  			fillWithEmptyRows(avgCols, data.getRowCount());
  
  			double step = original.getColumnCount() / (double) getColumnCount();
  			for (int rowIndex = 0; rowIndex < data.getRowCount(); rowIndex++) {
  				Row rowData = data.getRow(rowIndex);
  				for (int colIndex = 0; colIndex < getColumnCount(); colIndex++) {
  					double start = colIndex*step;
  					double end   = (colIndex + 1)*step;
  					avgCols.set(colIndex, rowIndex,
  							average(rowData, start, end));
  				}
  			}
  			data = avgCols;
  		}
  
  		for (int rowIndex = 0; rowIndex < data.getRowCount(); rowIndex++) {
  			Row row = data.getRow(rowIndex);
  			Comparable<?>[] rowData = row.toArray(null);
  			Double[] rowValues = new Double[rowData.length];
  			System.arraycopy(rowData, 0, rowValues, 0, rowValues.length);
  			add(rowValues);
  		}
  	}
  
  	/**
  	 * Utility method that fills a data table with empty rows.
  	 * @param data Data table that should be filled.
  	 * @param count Number of rows that were added.
  	 */
  	private static void fillWithEmptyRows(DataTable data, int count) {
  		while (data.getRowCount() < count) {
  			Double[] emptyRow = new Double[data.getColumnCount()];
  			Arrays.fill(emptyRow, 0.0);
  			data.add(emptyRow);
  		}
  	}
  
  	/**
  	 * Calculates the arithmetic mean of all values between start and end.
  	 * @param data Values.
  	 * @param start Start index.
  	 * @param end End index.
  	 * @return Arithmetic mean.
  	 */
  	private static double average(DataAccessor data, double start, double end) {
  		int startFloor = (int) Math.floor(start);
  		int startCeil  = (int) Math.ceil(start);
  		int endFloor = (int) Math.floor(end);
  		int endCeil = (int) Math.ceil(end);
  
  		double sum = 0.0;
  		for (int i = startFloor; i < endCeil; i++) {
  			Number number = (Number) data.get(i);
  			double val = number.doubleValue();
  			if (i == startFloor && startCeil != start) {
  				sum += (startCeil - start) * val;
  			} else if (i == endCeil - 1 && endFloor != end) {
  				sum += (end - endFloor) * val;
  			} else {
  				sum += val;
  			}
  		}
  		return sum / (end - start);
  	}
  
  	/**
  	 * Custom deserialization method.
  	 * @param in Input stream.
  	 * @throws ClassNotFoundException if a serialized class doesn't exist anymore.
  	 * @throws IOException if there is an error while reading data from the
  	 *         input stream.
  	 */
  	private void readObject(ObjectInputStream in)
  			throws ClassNotFoundException, IOException {
  		// Normal deserialization
  		in.defaultReadObject();
  
  		// Update caches
  		dataUpdated(this);
  	}
  }
  