src/plot/Contour.php
<?php
/**
* JPGraph v4.0.3
*/
namespace Amenadiel\JpGraph\Plot;
use Amenadiel\JpGraph\Image;
use Amenadiel\JpGraph\Util;
/*
* File: JPGRAPH_CONTOUR.PHP
* // Description: Contour plot
* // Created: 2009-03-08
* // Ver: $Id: jpgraph_contour.php 1870 2009-09-29 04:24:18Z ljp $
* //
* // Copyright (c) Asial Corporation. All rights reserved.
*/
define('HORIZ_EDGE', 0);
define('VERT_EDGE', 1);
/**
* This class encapsulates the core contour plot algorithm. It will find the path
* of the specified isobars in the data matrix specified. It is assumed that the
* data matrix models an equspaced X-Y mesh of datavalues corresponding to the Z
* values.
*/
class Contour
{
private $dataPoints = [];
private $nbrCols = 0;
private $nbrRows = 0;
private $horizEdges = [];
private $vertEdges = [];
private $isobarValues = [];
private $stack;
private $isobarCoord = [];
private $nbrIsobars = 10;
private $isobarColors = [];
private $invert = true;
private $highcontrast = false;
private $highcontrastbw = false;
/**
* Create a new contour level "algorithm machine".
*
* @param $aMatrix The values to find the contour from
* @param $aIsobars Mixed. If integer it determines the number of isobars to be used. The levels are determined
* automatically as equdistance between the min and max value of the matrice.
* If $aIsobars is an array then this is interpretated as an array of values to be used as isobars in the
* contour plot.
* @param null|mixed $aColors
*
* @return an instance of the contour algorithm
*/
public function __construct($aMatrix, $aIsobars = 10, $aColors = null)
{
$this->nbrRows = safe_count($aMatrix);
$this->nbrCols = safe_count($aMatrix[0]);
$this->dataPoints = $aMatrix;
if (is_array($aIsobars)) {
// use the isobar values supplied
$this->nbrIsobars = safe_count($aIsobars);
$this->isobarValues = $aIsobars;
} else {
// Determine the isobar values automatically
$this->nbrIsobars = $aIsobars;
list($min, $max) = $this->getMinMaxVal();
$stepSize = ($max - $min) / $aIsobars;
$isobar = $min + $stepSize / 2;
for ($i = 0; $i < $aIsobars; ++$i) {
$this->isobarValues[$i] = $isobar;
$isobar += $stepSize;
}
}
if ($aColors !== null && safe_count($aColors) > 0) {
if (!is_array($aColors)) {
Util\JpGraphError::RaiseL(28001);
//'Third argument to Contour must be an array of colors.'
}
if (safe_count($aColors) != safe_count($this->isobarValues)) {
Util\JpGraphError::RaiseL(28002);
//'Number of colors must equal the number of isobar lines specified';
}
$this->isobarColors = $aColors;
}
}
/**
* Flip the plot around the Y-coordinate. This has the same affect as flipping the input
* data matrice.
*
* @param $aFlg If true the the vertice in input data matrice position (0,0) corresponds to the top left
* corner of teh plot otherwise it will correspond to the bottom left corner (a horizontal flip)
*/
public function SetInvert($aFlg = true)
{
$this->invert = $aFlg;
}
/**
* Find the min and max values in the data matrice.
*
* @return array(min_value,max_value)
*/
public function getMinMaxVal()
{
$min = $this->dataPoints[0][0];
$max = $this->dataPoints[0][0];
for ($i = 0; $i < $this->nbrRows; ++$i) {
if (($mi = min($this->dataPoints[$i])) < $min) {
$min = $mi;
}
if (($ma = max($this->dataPoints[$i])) > $max) {
$max = $ma;
}
}
return [$min, $max];
}
/**
* Reset the two matrices that keeps track on where the isobars crosses the
* horizontal and vertical edges.
*/
public function resetEdgeMatrices()
{
for ($k = 0; $k < 2; ++$k) {
for ($i = 0; $i <= $this->nbrRows; ++$i) {
for ($j = 0; $j <= $this->nbrCols; ++$j) {
$this->edges[$k][$i][$j] = false;
}
}
}
}
/**
* Determine if the specified isobar crosses the horizontal edge specified by its row and column.
*
* @param $aRow Row index of edge to be checked
* @param $aCol Col index of edge to be checked
* @param $aIsobar Isobar value
*
* @return true if the isobar is crossing this edge
*/
public function isobarHCrossing($aRow, $aCol, $aIsobar)
{
if ($aCol >= $this->nbrCols - 1) {
Util\JpGraphError::RaiseL(28003, $aCol);
//'ContourPlot Internal Error: isobarHCrossing: Coloumn index too large (%d)'
}
if ($aRow >= $this->nbrRows) {
Util\JpGraphError::RaiseL(28004, $aRow);
//'ContourPlot Internal Error: isobarHCrossing: Row index too large (%d)'
}
$v1 = $this->dataPoints[$aRow][$aCol];
$v2 = $this->dataPoints[$aRow][$aCol + 1];
return ($aIsobar - $v1) * ($aIsobar - $v2) < 0;
}
/**
* Determine if the specified isobar crosses the vertical edge specified by its row and column.
*
* @param $aRow Row index of edge to be checked
* @param $aCol Col index of edge to be checked
* @param $aIsobar Isobar value
*
* @return true if the isobar is crossing this edge
*/
public function isobarVCrossing($aRow, $aCol, $aIsobar)
{
if ($aRow >= $this->nbrRows - 1) {
Util\JpGraphError::RaiseL(28005, $aRow);
//'isobarVCrossing: Row index too large
}
if ($aCol >= $this->nbrCols) {
Util\JpGraphError::RaiseL(28006, $aCol);
//'isobarVCrossing: Col index too large
}
$v1 = $this->dataPoints[$aRow][$aCol];
$v2 = $this->dataPoints[$aRow + 1][$aCol];
return ($aIsobar - $v1) * ($aIsobar - $v2) < 0;
}
/**
* Determine all edges, horizontal and vertical that the specified isobar crosses. The crossings
* are recorded in the two edge matrices.
*
* @param $aIsobar The value of the isobar to be checked
*/
public function determineIsobarEdgeCrossings($aIsobar)
{
$ib = $this->isobarValues[$aIsobar];
for ($i = 0; $i < $this->nbrRows - 1; ++$i) {
for ($j = 0; $j < $this->nbrCols - 1; ++$j) {
$this->edges[HORIZ_EDGE][$i][$j] = $this->isobarHCrossing($i, $j, $ib);
$this->edges[VERT_EDGE][$i][$j] = $this->isobarVCrossing($i, $j, $ib);
}
}
// We now have the bottom and rightmost edges unsearched
for ($i = 0; $i < $this->nbrRows - 1; ++$i) {
$this->edges[VERT_EDGE][$i][$j] = $this->isobarVCrossing($i, $this->nbrCols - 1, $ib);
}
for ($j = 0; $j < $this->nbrCols - 1; ++$j) {
$this->edges[HORIZ_EDGE][$i][$j] = $this->isobarHCrossing($this->nbrRows - 1, $j, $ib);
}
}
/**
* Return the normalized coordinates for the crossing of the specified edge with the specified
* isobar- The crossing is simpy detrmined with a linear interpolation between the two vertices
* on each side of the edge and the value of the isobar.
*
* @param $aRow Row of edge
* @param $aCol Column of edge
* @param $aEdgeDir Determine if this is a horizontal or vertical edge
* @param $ib The isobar value
* @param mixed $aIsobarVal
*
* @return unknown_type
*/
public function getCrossingCoord($aRow, $aCol, $aEdgeDir, $aIsobarVal)
{
// In order to avoid numerical problem when two vertices are very close
// we have to check and avoid dividing by close to zero denumerator.
if ($aEdgeDir == HORIZ_EDGE) {
$d = abs($this->dataPoints[$aRow][$aCol] - $this->dataPoints[$aRow][$aCol + 1]);
if ($d > 0.001) {
$xcoord = $aCol + abs($aIsobarVal - $this->dataPoints[$aRow][$aCol]) / $d;
} else {
$xcoord = $aCol;
}
$ycoord = $aRow;
} else {
$d = abs($this->dataPoints[$aRow][$aCol] - $this->dataPoints[$aRow + 1][$aCol]);
if ($d > 0.001) {
$ycoord = $aRow + abs($aIsobarVal - $this->dataPoints[$aRow][$aCol]) / $d;
} else {
$ycoord = $aRow;
}
$xcoord = $aCol;
}
if ($this->invert) {
$ycoord = $this->nbrRows - 1 - $ycoord;
}
return [$xcoord, $ycoord];
}
/**
* In order to avoid all kinds of unpleasent extra checks and complex boundary
* controls for the degenerated case where the contour levels exactly crosses
* one of the vertices we add a very small delta (0.1%) to the data point value.
* This has no visible affect but it makes the code sooooo much cleaner.
*/
public function adjustDataPointValues()
{
$ni = safe_count($this->isobarValues);
for ($k = 0; $k < $ni; ++$k) {
$ib = $this->isobarValues[$k];
for ($row = 0; $row < $this->nbrRows - 1; ++$row) {
for ($col = 0; $col < $this->nbrCols - 1; ++$col) {
if (abs($this->dataPoints[$row][$col] - $ib) < 0.0001) {
$this->dataPoints[$row][$col] += $this->dataPoints[$row][$col] * 0.001;
}
}
}
}
}
/**
* @param $aFlg
* @param $aBW
*
* @return unknown_type
*/
public function UseHighContrastColor($aFlg = true, $aBW = false)
{
$this->highcontrast = $aFlg;
$this->highcontrastbw = $aBW;
}
/**
* Calculate suitable colors for each defined isobar.
*/
public function CalculateColors()
{
if ($this->highcontrast) {
if ($this->highcontrastbw) {
for ($ib = 0; $ib < $this->nbrIsobars; ++$ib) {
$this->isobarColors[$ib] = 'black';
}
} else {
// Use only blue/red scale
$step = round(255 / ($this->nbrIsobars - 1));
for ($ib = 0; $ib < $this->nbrIsobars; ++$ib) {
$this->isobarColors[$ib] = [$ib * $step, 50, 255 - $ib * $step];
}
}
} else {
$n = $this->nbrIsobars;
$v = 0;
$step = 1 / ($this->nbrIsobars - 1);
for ($ib = 0; $ib < $this->nbrIsobars; ++$ib) {
$this->isobarColors[$ib] = Image\RGB::GetSpectrum($v);
$v += $step;
}
}
}
/**
* This is where the main work is done. For each isobar the crossing of the edges are determined
* and then each cell is analyzed to find the 0, 2 or 4 crossings. Then the normalized coordinate
* for the crossings are determined and pushed on to the isobar stack. When the method is finished
* the $isobarCoord will hold one arrayfor each isobar where all the line segments that makes
* up the contour plot are stored.
*
* @return array( $isobarCoord, $isobarValues, $isobarColors )
*/
public function getIsobars()
{
$this->adjustDataPointValues();
for ($isobar = 0; $isobar < $this->nbrIsobars; ++$isobar) {
$ib = $this->isobarValues[$isobar];
$this->resetEdgeMatrices();
$this->determineIsobarEdgeCrossings($isobar);
$this->isobarCoord[$isobar] = [];
$ncoord = 0;
for ($row = 0; $row < $this->nbrRows - 1; ++$row) {
for ($col = 0; $col < $this->nbrCols - 1; ++$col) {
// Find out how many crossings around the edges
$n = 0;
if ($this->edges[HORIZ_EDGE][$row][$col]) {
$neigh[$n++] = [$row, $col, HORIZ_EDGE];
}
if ($this->edges[HORIZ_EDGE][$row + 1][$col]) {
$neigh[$n++] = [$row + 1, $col, HORIZ_EDGE];
}
if ($this->edges[VERT_EDGE][$row][$col]) {
$neigh[$n++] = [$row, $col, VERT_EDGE];
}
if ($this->edges[VERT_EDGE][$row][$col + 1]) {
$neigh[$n++] = [$row, $col + 1, VERT_EDGE];
}
if ($n == 2) {
$n1 = 0;
$n2 = 1;
$this->isobarCoord[$isobar][$ncoord++] = [
$this->getCrossingCoord($neigh[$n1][0], $neigh[$n1][1], $neigh[$n1][2], $ib),
$this->getCrossingCoord($neigh[$n2][0], $neigh[$n2][1], $neigh[$n2][2], $ib), ];
} elseif ($n == 4) {
// We must determine how to connect the edges either northwest->southeast or
// northeast->southwest. We do that by calculating the imaginary middle value of
// the cell by averaging the for corners. This will compared with the value of the
// top left corner will help determine the orientation of the ridge/creek
$midval = ($this->dataPoints[$row][$col] + $this->dataPoints[$row][$col + 1] + $this->dataPoints[$row + 1][$col] + $this->dataPoints[$row + 1][$col + 1]) / 4;
$v = $this->dataPoints[$row][$col];
if ($midval == $ib) {
// Orientation "+"
$n1 = 0;
$n2 = 1;
$n3 = 2;
$n4 = 3;
} elseif (($midval > $ib && $v > $ib) || ($midval < $ib && $v < $ib)) {
// Orientation of ridge/valley = "\"
$n1 = 0;
$n2 = 3;
$n3 = 2;
$n4 = 1;
} elseif (($midval > $ib && $v < $ib) || ($midval < $ib && $v > $ib)) {
// Orientation of ridge/valley = "/"
$n1 = 0;
$n2 = 2;
$n3 = 3;
$n4 = 1;
}
$this->isobarCoord[$isobar][$ncoord++] = [
$this->getCrossingCoord($neigh[$n1][0], $neigh[$n1][1], $neigh[$n1][2], $ib),
$this->getCrossingCoord($neigh[$n2][0], $neigh[$n2][1], $neigh[$n2][2], $ib), ];
$this->isobarCoord[$isobar][$ncoord++] = [
$this->getCrossingCoord($neigh[$n3][0], $neigh[$n3][1], $neigh[$n3][2], $ib),
$this->getCrossingCoord($neigh[$n4][0], $neigh[$n4][1], $neigh[$n4][2], $ib), ];
}
}
}
}
if (safe_count($this->isobarColors) == 0) {
// No manually specified colors. Calculate them automatically.
$this->CalculateColors();
}
return [$this->isobarCoord, $this->isobarValues, $this->isobarColors];
}
}
// EOF