How to change value with count data - json

Question

I have json data with value but instead of display the value i want to display the count of value which is not in my json data. How to make var like select count(*) from ecgvalue?.
This is my code
<script type="text/javascript">
$(function () {
var processed_json = new Array();
$.getJSON('http://localhost:8080/query', function (data) {
// Populate series
for (i = 0; i < data.length; i++) {
processed_json.push([data[i].id_data, data[i].ecgvalue]);
}
// draw chart
$('#container2').highcharts({
chart: {
type: "column"
},
title: {
text: "ECG Graph"
},
xAxis: {
type: 'category',
allowDecimals: false,
title: {
text: "Id Data"
}
},
yAxis: {
title: {
text: "Value"
}
},
series: [{
name: 'ECG value',
data: processed_json
}]
});
});
});
</script>
and this is my json
[{"id_data":1,"ecgvalue":3.3871},{"id_data":2,"ecgvalue":1.56892},{"id_data":3,"ecgvalue":1.60802},{"id_data":4,"ecgvalue":2.09677},{"id_data":5,"ecgvalue":1.99902},{"id_data":6,"ecgvalue":1.97947}]
I want to change value of y axis to count from ecgvalue, is that possible?

Answer 1

If by count you mean how many items are in the processed_json array (as you can with the SQL statement count(*)), then all you need is simply processed_json.length.
Here's a working example using the data you provided: https://jsfiddle.net/brightmatrix/t8pv7csn/
You can then use the processed_json.length however you wish in your code and/or chart options.

Answer 2

<script type="text/javascript">
$(function () {
var processed_json = new Array();
$.getJSON('http://localhost:8080/query', function (data) {
// Populate series
var ecgCount = 0;
for (i = 0; i < data.length; i++) {
ecgCount += data[i].ecgvalue
processed_json.push([data[i].id_data, data[i].ecgvalue]);
}
// draw chart
$('#container2').highcharts({
chart: {
type: "column"
},
title: {
text: "ECG Graph"
},
xAxis: {
type: 'category',
allowDecimals: false,
title: {
text: "Id Data"
}
},
yAxis: {
title: {
text: ecgCount
}
},
series: [{
name: 'ECG value',
data: processed_json
}]
});
});
});
</script>
Is this What you required.