Javascript, using Highcharts to display a chart of rankings with JSON Data - php

Question

I am trying to use javascript Highcharts to display a chart of rankings from JSON data. I can't seem to get the chart to display.
This is the javascript code:
$(document).ready(function() {
var options = {
chart: {
renderTo: 'drawing',
zoomType: 'x',
width: 900,
height: 222
},
exporting: {
enabled:true
},
title: {
text: url+' - '+keyword
},
credits: {
text: '****',
href: 'http://***/'
},
xAxis: {
type: 'datetime',
dateTimeLabelFormats: {
day: '%b %e '
}
},
yAxis: [{
//min: 1,
allowDecimals: false,
reversed: true,
///: .2,
//maxPadding: .2,
title: {
text: 'Rankings'
}
},],
tooltip: {
crosshairs: true,
shared: true
},
series: [{}]
};
var url = "http://*******/chart.php";
$.getJSON(url, function(data) {
$.each(data, function(arrayID,group) {
$.each(group.data, function(id,val) {
arg = val[0].replace(/Date.UTC\((.*?)\)/, '$1').split(',');
var timestamp = Date.UTC.apply( null , arg );
date=new Date(timestamp);
data[arrayID].data[id][0] = timestamp;
});
});
options.series[0].data = data;
var chart = new Highcharts.Chart(options);
});
});
Our PHP Script gives us this JSON:
[{"name":"Google Rank","data":[["Date.UTC(2013,04,05)","23"],["Date.UTC(2013,04,04)","23"],["Date.UTC(2013,04,03)","22"],["Date.UTC(2013,04,02)","24"],["Date.UTC(2013,04,01)","26"],["Date.UTC(2013,03,31)","24"],["Date.UTC(2013,03,30)","24"],["Date.UTC(2013,03,29)","25"],["Date.UTC(2013,03,28)","25"],["Date.UTC(2013,03,27)","25"],["Date.UTC(2013,03,26)","26"],["Date.UTC(2013,03,25)","25"],["Date.UTC(2013,03,24)","24"],["Date.UTC(2013,03,23)","-"],["Date.UTC(2013,03,22)","10"],["Date.UTC(2013,03,21)","10"],["Date.UTC(2013,03,20)","10"],["Date.UTC(2013,03,19)","10"],["Date.UTC(2013,03,18)","10"],["Date.UTC(2013,03,17)","10"],["Date.UTC(2013,03,16)","9"],["Date.UTC(2013,03,15)","9"],["Date.UTC(2013,03,14)","9"],["Date.UTC(2013,03,13)","9"],["Date.UTC(2013,03,12)","9"]],"visible":"true","pointInterval":"86400000","showInLegend":"false"},{"name":"Bing Rank","data":["Date.UTC(2013,2,9)",9],"visible":"true","pointInterval":"86400000","showInLegend":"false"}]
Note the JSON data represents numbers as strings which could be a problem.
PHP Code which generates the JSON data:
$googledata = array();
while($gkdata = mysql_fetch_assoc($keywordquery)){
$explodedate = explode("-", $gkdata['date']);
$year = $explodedate[0];
$month = $explodedate[1];
$day = $explodedate[2];
$googledata[] = array(
"".$year.",".$month.",".$day."",
$gkdata['grank'] //$gkdata['grank'] should be a number, but is sometimes a dash so it's cast to an accommodating datatype: string.
);
}
$chartdata = array(
array(
"name" => 'Google Rank',
"data" => $googledata,
"visible" => 'true',
"pointInterval" => '86400000',
"showInLegend" => 'false',
),
array(
"name" => 'Bing Rank',
"data" => array(
'Date.UTC(2013,2,9)',
9
),
"visible" => 'true',
"pointInterval" => '86400000',
"showInLegend" => 'false',
)
);
The Highcharts won't display anything other than the chart itself with no data. The Date.UTC(2013,03,12) is supposed to go on the X-Axis & the number next to it is supposed to be the rank number. Can anyone see what is wrong?

Answer 1

The chart takes data as [x,y]. You just need to reverse the order of your data to ['value',datestamp'] if you want the date to be on the y axis.
Edit:
I am not sure from the text what the problem you are having is, but one problem that will arise from your code is that your number data values are being returned as strings, in quotes.
You will need to cast them as integers in your php before json encoding in order for them to come through unquoted, as integers.
You should be seeing an error from this: http://www.highcharts.com/errors/14

Answer 2

You are expecting $gkdata['grank'] to always return a number, it sometimes returns a dash -. The Array Object is using the datatype which best represents the data, and it chooses string. If you want to force it as int, you'll have to use a data structure that only allows integers to be put in it. Then it will puke when you try to put in a dash, which it should be doing, because how do you plot a DASH on a chart?
Had you taken off your blindfold, and looked at the error HighCharts returned to you, you would see this:
Highcharts Error #14 String value sent to series.data, expected Number
This happens if you pass in a string as a data point, for example in a setup like this:
series: [{
data: ["3", "5", "1", "6"]
}]
Highcharts expects the data values to be numbers. The most common reason for this is that data is parsed from CSV or from a XML source, and the implementer forgot to run parseFloat on the parsed value.
For performance reasons internal type casting is not performed, and only the first value is checked (since 2.3).
So fix your code to make grank always a number. HighCharts won't plot strings for performance reasons.