overlaying graphs.

[PrakashGaonkar]

http://www.phplot.com/phplotdocs/ex-outbreak.html
I am using this example.

My data is dynamic fetched from a csv file. The Y axis range can vary a lot.
I need to overlay 2 charts such as they are independent. But in my code data1 plots fine.
Data2 uses the Y axis (Right side) range same as Data1.
I want data2 Y axis to use it's own data range. whatever phplot automatically calculates.

code is as below.

    require_once 'phplot.php';

    $title = 'GDVM Rank vs Close';
    $y_title1 = 'Weekly Rank';
            # data1 $rank_ data is dynamic
    $data1 = array(
    array('12_13_2014',$Rank_12_13_2014),
    array('12_20_2014',$Rank_12_20_2014),
    array('12_27_2014',$Rank_12_27_2014),
    array('01_03_2015',$Rank_01_03_2015),
    array('01_10_2015',$Rank_01_10_2015),
    array('03_14_2015',$Rank_03_14_2015)        
                        );
    $legend1 = array('Weekly Rank');

    # Data for plot #2: linepoints:
    $y_title2 = 'Weekly Close'  ;
            # data2 $close_ data is dynamic             
    $data2 = array(
    array('12_13_2014',$Close_12_13_2014),
    array('12_20_2014',$Close_12_20_2014),
    array('12_27_2014',$Close_12_27_2014),
    array('01_03_2015',$Close_01_03_2015),
    array('01_10_2015',$Close_01_10_2015),
    array('03_14_2015',$Close_03_14_2015)       
                        );                  
    $legend2 = array('Weekly Close');

    $plot =& new PHPlot(1000,600);
    $plot->SetImageBorderType('plain'); // For presentation in the manual
    $plot->SetPrintImage(False);  // Do not output the image
    $plot->SetTitle($title);
    $plot->SetPlotBgColor('gray');
    $plot->SetLightGridColor('black'); // So grid stands out from background

        # Plot 1
    $plot->SetDrawPlotAreaBackground(True);
    $plot->SetPlotType('stackedbars');
    $plot->SetDataType('text-data');
    $plot->SetDataValues($data1);
    $plot->SetYTitle($y_title1);
    # Set and position legend #1:
    $plot->SetLegend($legend1);
    $plot->SetLegendPixels(5, 30);
    # Set margins to leave room for plot 2 Y title on the right.
    $plot->SetMarginsPixels(120, 120);
    # Specify Y range of these data sets:
    //$plot->SetPlotAreaWorld(NULL, 0, NULL, 5000);
    //$plot->SetYTickIncrement(500);
    $plot->SetXTickLabelPos('none');
    $plot->SetXTickPos('none');
    # Format Y tick labels as integers, with thousands separator:
    //$plot->SetYLabelType('data', 0);
    //$plot->TuneYAutoRange(10, 'Decimal');
    $plot->SetYLabelType('data', 1);
    $plot->DrawGraph();

    # Plot 2
    $plot->SetDrawPlotAreaBackground(False); // Cancel background
    $plot->SetDrawYGrid(False); // Cancel grid, already drawn
    $plot->SetPlotType('linepoints');
    $plot->SetDataValues($data2);
    # Set Y title for plot #2 and position it on the right side:
    $plot->SetYTitle($y_title2, 'plotright');
    # Set and position legend #2:
    $plot->SetLegend($legend2);
    $plot->SetLegendPixels(690, 30);
    # Specify Y range of this data set:
    //$plot->SetPlotAreaWorld(NULL, 0, NULL, 50);
    //$plot->SetYTickIncrement(10);
    //$plot->TuneYAutoRange(10, 'binary');
    $plot->SetYTickPos('plotright');
    $plot->SetYTickLabelPos('plotright');
    $plot->SetDataColors('black');
    # Format Y tick labels as integers with trailing percent sign:
    //$plot->SetYLabelType('data', 0, '', '%');
    $plot->SetYLabelType('data', 1);
    $plot->DrawGraph();

    //$graph->DrawGraph();
    echo "<img src=\"" . $plot->EncodeImage() . "\">\n";

[PrakashGaonkar]

Basically in these 2 situations the same code should automatiocally adjust both Y axis intervalsd.

1: data1 changes in range 10 to 100
data2 changes in range 40 to 50.
2: data1 changes in range 1500 to 2000
data2 changes in range 10 to 20.

from my code, data1 (left Y axis) plots fine as barcharts.
the data2 (right Y axis) tries to follow data1's y axis range and it's not preety.

[PrakashGaonkar]

copying from elsewhere on the forum..

"PHPlot is supposed to automatically calculate a good range based on the data array for the first overlay, and then use the same range for the second - regardless of the second data array."

Now That is the problem. I want the second data array to use it's own range. Is it possible in PHPlot?

[PrakashGaonkar]

trial and Error....
I think below line solved my problem.(May be) Your comments are welcome.

$plot->SetPlotAreaWorld(NULL, 0, NULL, NULL);

[lbayuk]

Yes, you figured it out correctly. Each NULL argument to SetPlotAreaWorld tells PHPlot to calculate (or re-calculate, when used with overlays) a value for that limit. In your previous post, you are setting Ymin=0 and letting PHPlot recalculate Xmin, Xmax, and Ymax.

More details here: http://www.phplot.com/phplotdocs/adv-multiplot.html#adv-multiplot-datascale

[PrakashGaonkar]

Cool. Thanks. I think it is a terrific project.

[lbayuk]

Thanks. By the way, I noticed your example above has: $plot &= new PHPlot(...). You should not use & with new in any current version of PHP. (If you took this from an old copy of the PHPlot Reference Manual on a web site somewhere, please let me know where.)

[PrakashGaonkar]

Thanks. I will change the code to remove "&". I don't remember from where i picked that code. if I see it again, I will update the message with link.