PHP array into a Scatter chart

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Posted by Mark Carter on 21st May 2016
I am very new to RGraph.
I have an array in php called $arrData["Data"]. It has two variables, both numeric, and I want to plot these on a scatter plot.
This is the script that I am using, but I am sure it's incorrect. A chart appears but it is empty.
How do correct this so it will work please?

<script>
     window.onload = function ()
     {
         var data1 = <?php echo json_encode($arrData["Data"]) ?>;
        
         var scatter = new RGraph.Scatter({
             id: 'cvs',
             data: [data1],
             options: {
                 backgroundGridAutofitNumvlines: 12,
                 textAccessible: true
             }
         }).draw();
     };
</script>
Posted by Richard on 21st May 2016
Hi,

I think that all you need to do is specify an xmax option to set the maximum that the X axis will display. If you want to show a year this could be 365 for example, or if you want to show a week it could be 7. Something like this:

  var scatter = new RGraph.Scatter({
      id: 'cvs',
      data: [data1],
      options: {

          // Add a maximum for the X axis
          xmax: 365

          backgroundGridAutofitNumvlines: 12,
          textAccessible: true
      }
  }).draw();





Richard
Posted by Mark Carter on 23rd May 2016
Thanks for getting back to me Richard.

The x-axis is a variable in my array.

So, my array will look something like this:

"ld" = 0.3, 0.6, 1.2, 1.9
"rv" = -0.4, -0.0, 0.5, 0.9

Both "ld" and "rv" sets of values are in the php array called $arrData["Data"].

I would like "ld" to be the y-axis and "rv" to be the x-axis, with the 4 data points plotted accordingly.

Any help appreciated.

Mark
Posted by Richard on 23rd May 2016
Hi there,

Then you could do something like this:



<?php
     $arrData['Data'] = array(
         "ld" => array(0.3, 0.6, 1.2, 1.9),
         "rv" => array( -0.4, 0.0, 0.5, 0.9)
     );
    
     $data = json_encode($arrData['Data']);
?>


<script>
     src = <?php echo $data ?>;
     data = [];
    
     for (var i=0; i<src.ld.length; ++i) {
         data.push([src.ld[i], src.rv[i]]);
     }
</script>


You could then use the data array with your Scatter chart.





Richard
Posted by Mark Carter on 24th May 2016
Thanks for taking the time again Richard. However I still am unsure exactly how to use the data array with the scatter chart.

I have used your code above, and then what?

I have:

<?php
$data = json_encode($arrData['Data']);
?>
    
<script>
src = <?php echo $data ?>;
data = [];
for (var i=0; i<src.ld.length; ++i) {
data.push([src.ld[i], src.rv[i]]);
}

window.onload = function ()
{
var scatter = new RGraph.Scatter({
id: 'cvs',
data: $arrData['Data'];
options: {
        backgroundGridAutofitNumvlines: 12,
        textAccessible: true
        }
        }).draw();
     };
</script>
            
<canvas id="cvs" width="600" height="200">
     [No canvas support]
</canvas>
Posted by Richard on 24th May 2016
Hi,

After you do that code (that I posted) you could then use it to create your chart:




<script>
     var scatter = new RGraph.Scatter({
         id: 'cvs',

         // Here the label and the variable name
         // happen to be the same
         data: data,

         options: {
             backgroundGridAutofitNumvlines: 12,
             textAccessible: true
         }
     }).draw();
</script>


<canvas id="cvs" width="600" height="200">
      [No canvas support]
</canvas>







Richard
Posted by Mark Carter on 25th May 2016
OK - I tried exactly that - but no chart appears, just blank space.

Here is the <head> code:

<head>
<link rel="stylesheet" href="style.css">
<script src="RGraph/libraries/RGraph.common.core.js"></script>
<script src="RGraph/libraries/RGraph.scatter.js"></script>
<script src="RGraph/libraries/RGraph.common.dynamic.js"></script>
</head>

And here is the code that you have helped with:

<?php
$data = json_encode($arrData['Data']);
?>
    
<script>
      src = <?php echo $data ?>;
      data = [];
    
      for (var i=0; i<src.ld.length; ++i) {
          data.push([src.ld[i], src.rv[i]]);
      }
</script>

<script>
      var scatter = new RGraph.Scatter({
          id: 'cvs',

          // Here the label and the variable name
          // happen to be the same
          data: data,

          options: {
              backgroundGridAutofitNumvlines: 12,
              textAccessible: true
          }
      }).draw();
</script>
  
            
<canvas id="cvs" width="600" height="200">
     [No canvas support]
</canvas>


I wonder whether the problem is because of the array $arrData['Data'] and the way it is constructed?
When I echo $data after the line "$data = json_encode($arrData['Data']);", I get:

[{"ld":"0.35614","rv":0.24349555412625},{"ld":"0.84800","rv":-0.32906936661946},{"ld":"0.41143","rv":0.18244075177118},{"ld":"1.63227","rv":-0.17570669185289},{"ld":"0.84800","rv":0.052397407794944},{"ld":"1.07039","rv":-0.50674627736103},{"ld":"0.48543","rv":0.5835506153252},{"ld":"1.03562","rv":0.39591320240103},{"ld":"0.79077","rv":-0.015791029142252},{"ld":"0.58496","rv":-0.70114105329482}]

Your help will be appreciated - I'm sure it's something simple but I have tried so many things to fix it and still no luck!
Posted by Richard on 26th May 2016
Hi there,

There's an example here:

www.rgraph.net/tests/aa_data-structure.html

You'll need to view-source of course.





Richard
Posted by Mark Carter on 26th May 2016
Thanks again Richard.
Your example is helpful. However I still get a blank space where a chart should be.
I have compared the two source codes. My source code is below. It is identical to yours.
I think I will give up now, it's driving me crazy - but thanks again for all your efforts.
Mark

<script>
      src = [{"ld":"1.72247","rv":0.20719062725298},{"ld":"1.32193","rv":0.1137953478092},{"ld":"0.68706","rv":0.20198291835636},{"ld":"1.20163","rv":0.013502016096127},{"ld":"1.72247","rv":-0.1997614257191},{"ld":"1.58496","rv":-0.087827716068325},{"ld":"1.52105","rv":0.16947099911064},{"ld":"0.84800","rv":0.10918813124023},{"ld":"0.67807","rv":0.28076556904911},{"ld":"1.26303","rv":-0.010770803938336},{"ld":"0.68706","rv":0.11289331154612},{"ld":"1.03562","rv":0.35495988308629}];
      data = [];
    
         for (var i=0; i<src.length; i++) {
             data.push([
                 parseFloat(src[i].ld),
                 parseFloat(src[i].rv)
             ]);

         new RGraph.Scatter({
             id: 'cvs',
             data: data,
             options: {
                 xmax: 5,
                 scaleDecimals: 1,

                 xaxispos: 'center',
             }
         }).draw();
</script>

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