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drawBestFit - Draw the "line of best fit"

This function allows you to draw the line of best fit associated with your given data series. All the drawing parameters are given trough a $Format array. To learn more about this please read the Format array guide. The mathematical formula used to compute it is described below :



Calling this function
drawBestFit($Format="");
Where :

Format is an array containing the drawing parameters of the chart. (today none are defined)


Customisation array - Tune up your chart!

It is possible to customize the rendering by playing with this array. Providing a detailled configuration is not mandatory. You‘ll see below a representation of all the customization possible :

You can optionally specify the line ticks width with Ticks.


Sample script


 /* pChart library inclusions */
 include("../class/pData.class.php");
 include("../class/pDraw.class.php");
 include("../class/pImage.class.php");

 /* Create and populate the pData object */
 $MyData = new pData();  
 for($i=0;$i<=20;$i++) { $MyData->addPoints(rand(10,30)+$i,"Probe 1"); }
 for($i=0;$i<=20;$i++) { $MyData->addPoints(rand(0,10)+$i,"Probe 2"); }
 $MyData->setAxisName(0,"Temperatures");

 /* Create the pChart object */
 $myPicture = new pImage(700,230,$MyData);

 /* Turn of Antialiasing */
 $myPicture->Antialias = FALSE;

 /* Add a border to the picture */
 $myPicture->drawRectangle(0,0,699,229,array("R"=>0,"G"=>0,"B"=>0));
 
 /* Write the chart title */ 
 $myPicture->setFontProperties(array("FontName"=>"../fonts/Forgotte.ttf","FontSize"=>11));
 $myPicture->drawText(150,35,"Average temperature",array("FontSize"=>20,"Align"=>TEXT_ALIGN_BOTTOMMIDDLE));

 /* Set the default font */
 $myPicture->setFontProperties(array("FontName"=>"../fonts/pf_arma_five.ttf","FontSize"=>6));

 /* Define the chart area */
 $myPicture->setGraphArea(60,40,650,200);

 /* Draw the scale */
 $scaleSettings = array("XMargin"=>10,"YMargin"=>10, "Floating"=>TRUE,"GridR"=>200, "GridG"=>200,"GridB"=>200,"DrawSubTicks"=>TRUE, "CycleBackground"=>TRUE);
 $myPicture->drawScale($scaleSettings);

 /* Turn on Antialiasing */
 $myPicture->Antialias = TRUE;

 /* Draw the line of best fit */
 $myPicture->drawBestFit();

 /* Turn on shadows */
 $myPicture->setShadow(TRUE,array("X"=>1,"Y"=>1,"R"=>0,"G"=>0,"B"=>0,"Alpha"=>10));

 /* Draw the line chart */
 $myPicture->drawPlotChart();

 /* Write the chart legend */
 $myPicture->drawLegend(580,20,array("Style"=>LEGEND_NOBORDER,"Mode"=>LEGEND_HORIZONTAL));

 /* Render the picture (choose the best way) */
 $myPicture->autoOutput("pictures/example.drawBestFit.png");
Last updated on 01/26/2011 
by Jean-Damien 
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