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drawScatterThreshold- Draw a threshold in the scatter chart area

This function will draw a threshold in the scatter chart area. Using thresholds can help you to highlight specific values. It is possible to tune the rendering by playing with the $Format array. To learn more about this please read the Format array guide.

By default, the threshold will be drawn using the 1st Y Axis (0) as reference. If you chart contains multiple Y Axis, please use the AxisID parameter of the format array.

Calling this function
Where :

Value is the value (or an array of values) of the threshold to draw.
Format is an array containing the drawing parameters of the arrow.

This function returns an array containing the Y position of the threshold line.

Customisation array - Tune up your threshold!

It is possible to customize the way your threshold will be rendered by playing with this array. Providing a detailled configuration is not mandatory, by default the line will be drawn dashed in red.

You can specify which axis you‘ll use to compute the value position in the chart area with AxisID.
You can specify the line color using R,G,B.
You can specify the line alpha factor using Alpha.
You can specify the line tick width with Ticks.
You can choose to write a caption over the threshold setting WriteCaption to TRUE.
By default the value of the threshold will be written, this can be override setingCaption to whatever you want.
You can specify an offset to the alignement axis with CaptionOffset to TRUE.
The color of the caption can be set using CaptionR,CaptionG,CaptionB.
The alpha transparency of the caption can be set using CaptionAlpha.
You can specify if the threshold will reach the axis bar even if margin are defined setting NoMargin to TRUE.
You can decide to draw a box under the caption setting DrawBox. to TRUE.

If you choose to draw a box under the caption, all the drawText() extended styles can be used (DrawBoxBorder,BorderOffset,BoxRounded, ...) to have the complete list of parameters, take a look at the drawText() page.

The captions can be aligned using CaptionAlign the following ways :

CAPTION_LEFT_TOP on the left or top side (depending of the scale orientation).
CAPTION_RIGHT_BOTTOM on the right or bottom side (depending of the scale orientation).

Sample script

 /* pChart library inclusions */ 

 /* Create the pData object */ 
 $myData = new pData();   

 /* Create the X axis and the binded series */ 
 $myData->setAxisName(0,"x = 1/z"); 

 /* Create the Y axis */ 
 $myData->setAxisName(1,"y = z"); 

 /* Create the Y axis */ 
 $myData->setAxisName(2,"y = z*z*z"); 

 /* Create the 1st scatter chart binding */ 
 $myData->setScatterSerieDescription(0,"Pass A"); 

 /* Create the 2nd scatter chart binding */ 
 $myData->setScatterSerieDescription(1,"Pass B"); 

 /* Create the pChart object */ 
 $myPicture = new pImage(400,400,$myData); 

 /* Draw the background */ 
 $Settings = array("R"=>170, "G"=>183, "B"=>87, "Dash"=>1, "DashR"=>190, "DashG"=>203, "DashB"=>107);

 /* Overlay with a gradient */ 
 $Settings = array("StartR"=>219, "StartG"=>231, "StartB"=>139, "EndR"=>1, "EndG"=>138, "EndB"=>68, "Alpha"=>50);
 $myPicture->drawGradientArea(0,0,400,20,DIRECTION_VERTICAL,array("StartR"=>0,"StartG"=>0, "StartB"=>0,"EndR"=>50,"EndG"=>50,"EndB"=>50,"Alpha"=>80));
 /* Write the picture title */  
 $myPicture->drawText(10,13,"createFunctionSerie() - Functions computing",array("R"=>255,"G"=>255,"B"=>255));
 /* Add a border to the picture */ 

 /* Set the default font */ 
 /* Set the graph area */ 

 /* Create the Scatter chart object */ 
 $myScatter = new pScatter($myPicture,$myData); 

 /* Draw the scale */ 
 /* Turn on shadow computing */ 
 /* Draw the 0/0 lines */ 
 /* Draw a treshold area */ 
 $myScatter->drawScatterThresholdArea(-0.1,0.1,array("AreaName"=>"Error zone"));
 /* Draw a scatter plot chart */ 

 /* Draw the legend */ 
 /* Render the picture (choose the best way) */ 
Last updated on 09/09/2011 
by Jean-Damien 
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