GraphLine.php

   1 <?php
   2 /*=====================================================================*
   3 || ###################################################################
   4 || # Blue Static ISSO Framework
   5 || # Copyright ©2002-[#]year[#] Blue Static
   6 || #
   7 || # This program is free software; you can redistribute it and/or modify
   8 || # it under the terms of the GNU General Public License as published by
   9 || # the Free Software Foundation; version [#]gpl[#] of the License.
  10 || #
  11 || # This program is distributed in the hope that it will be useful, but
  12 || # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13 || # or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  14 || # more details.
  15 || #
  16 || # You should have received a copy of the GNU General Public License along
  17 || # with this program; if not, write to the Free Software Foundation, Inc.,
  18 || # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
  19 || ###################################################################
  20 \*=====================================================================*/
  21
  22 /**
  23 * Graphing System: Line Graph (GraphLine.php)
  24 *
  25 * @package      ISSO
  26 */
  27
  28 require_once('ISSO/Graph.php');
  29
  30 /**
  31 * Graphing System: Line Graph
  32 *
  33 * This creates a line graph from a set of data; each point requires
  34 * a line name (because this supports multi-line graphing), an x-value,
  35 * and a y-value. It creates PNG images.
  36 *
  37 * @author               Blue Static
  38 * @copyright    Copyright (c)2002 - [#]year[#], Blue Static
  39 * @version              $Revision$
  40 * @package              ISSO
  41 *
  42 */
  43 class BSGraphLine extends BSGraph
  44 {
  45         /**
  46         * Graphing dataset; 4D array
  47         * array(array(name, array(array(xval, yval))), color)
  48         * @var string
  49         */
  50         protected $dataset = array();
  51
  52         /**
  53         * Array of data points that are used to calculate the standard deviation
  54         * @var array
  55         */
  56         private $piles = array(0 => array(), 1 => array());
  57
  58         // ###################################################################
  59         /**
  60         * Does the actual graphing and returns a byte stream of a PNG image
  61         *
  62         * @return       string  Byte stream
  63         */
  64         public function graph()
  65         {
  66                 // calculates the standard deviation of the two piles to determine the x and y intervals
  67                 $xint = $this->_standardDeviation($this->piles[0]);
  68                 $yint = $this->_standardDeviation($this->piles[1]);
  69
  70                 $xmin = min($this->piles[0]);
  71                 $xmin = ($xmin - $xint < 0 ? 0 : $xmin - $xint);
  72                 $xmax = max($this->piles[0]) + $xint;
  73
  74                 $ymin = min($this->piles[1]);
  75                 $ymin = ($ymin - $int < 0 ? 0 : $ymin - $yint);
  76                 $ymax = max($this->piles[1]) + $yint;
  77
  78
  79         }
  80
  81         // ###################################################################
  82         /**
  83         * Adds a "line" with a given name and a set of datapoints in the form
  84         * array(x, y)
  85         *
  86         * @param        string  The line's name
  87         * @param        array   Array of array(x,y) as data points
  88         */
  89         public function addDataSet($name, $points)
  90         {
  91                 $this->_addPoints($points);
  92                 $this->_sortPoints($points);
  93                 $this->dataset[] = array($name, $points, $this->_fetchColor());
  94         }
  95
  96         // ###################################################################
  97         /**
  98         * This does the same thing as addDataSet(), except the client code
  99         * can specify the color in the form of array(R, G, B)
 100         *
 101         * @param        string  The line's name
 102         * @param        array   Array of array(x,y) as data points
 103         * @param        array   A color in the form of 3 RGB points
 104         */
 105         public function addDataSetColor($name, $points, $color)
 106         {
 107                 $this->_addPoints($points);
 108                 $this->_sortPoints($points);
 109                 $this->dataset[] = array($name, $points, imagecolorallocate($this->image, $color[0], $color[1], $color[2]));
 110         }
 111
 112         // ###################################################################
 113         /**
 114         * Adds a set of points to the piles and ensures that they are all valid
 115         *
 116         * @param        array   Points to add
 117         */
 118         private function _addPoints($points)
 119         {
 120                 $xpairs = array();
 121                 foreach ($points AS $point)
 122                 {
 123                         if (isset($xpairs["$point[0]"]))
 124                         {
 125                                 trigger_error('You cannot have more than one of the same x-values for a given data set');
 126                         }
 127                         $xpairs["$point[0]"] = $point[0];
 128                         $this->piles[0][] = $point[0];
 129                         $this->piles[1][] = $point[1];
 130                 }
 131         }
 132
 133         // ###################################################################
 134         /**
 135         * Sorts an array of points using quick sort so they're in x-increasing
 136         * order
 137         *
 138         * @param        array   Array of points
 139         */
 140         private function _sortPoints(&$points)
 141         {
 142                 $this->_quickSortPoints($points, 0, sizeof($points) - 1);
 143         }
 144
 145         // ###################################################################
 146         /**
 147         * Quicksort function for sorting function
 148         *
 149         * @param        array   Array of points
 150         * @param        integer Lower bound
 151         * @param        integer Upper bound
 152         */
 153         private function _quickSortPoints(&$points, $low, $high)
 154         {
 155                 if (($high - $low) > 1)
 156                 {
 157                         $partition = $this->_partitionPoints($points, $low, $high);
 158                         $this->_quickSortPoints($points, $low, $partition);
 159                         $this->_quickSortPoints($points, $partition + 1, $high);
 160                 }
 161         }
 162
 163         // ###################################################################
 164         /**
 165         * Quicksort partitioner: returns the index of the pivot element where
 166         * all x-coords on the left side of pivot are less than or equal to
 167         * pivot, and all x-coords are higher to the right
 168         *
 169         * @param        array   Array of points
 170         * @param        integer Lower bound
 171         * @param        integer Upper bound
 172         *
 173         * @return       integer Pivot index
 174         */
 175         private function _partitionPoints(&$points, $low, $high)
 176         {
 177                 $pivot = $low;
 178                 for ($unsorted = $low + 1; $unsorted <= $high; $unsorted++)
 179                 {
 180                         if ($points[$unsorted][0] < $points[$pivot][0])
 181                         {
 182                                 $temp = $points[$pivot];
 183                                 $points[$pivot] = $points[$unsorted];
 184                                 $points[$unsorted] = $points[$pivot + 1];
 185                                 $points[$pivot + 1] = $temp;
 186                                 $pivot++;
 187                         }
 188                 }
 189                 return $pivot;
 190         }
 191
 192         // ###################################################################
 193         /**
 194         * Returns the unbiased statistical standard deviation of an array of
 195         * values
 196         *
 197         * @param        array   Array of values
 198         *
 199         * @return       float   Standard deviation (unbiased)
 200         */
 201         private function _standardDeviation($vals)
 202         {
 203                 $average = $this->_arrayAverage($vals);
 204                 $popVariance = array();
 205
 206                 foreach ($vals AS $val)
 207                 {
 208                         $popVariance[] = pow($val - $average, 2);
 209                 }
 210
 211                 return sqrt($this->_arrayAverage($popVariance));
 212         }
 213
 214         // ###################################################################
 215         /**
 216         * Returns the stastical mean of an array of values
 217         *
 218         * @param        array   Array of values
 219         *
 220         * @return       float   Statistical mean
 221         */
 222         private function _arrayAverage($vals)
 223         {
 224                 return array_sum($vals) / count($vals);
 225         }
 226 }
 227
 228 /*=====================================================================*
 229 || ###################################################################
 230 || # $HeadURL$
 231 || # $Id$
 232 || ###################################################################
 233 \*=====================================================================*/
 234 ?>