Logarithmic axis in EJ2 JavaScript Chart control

8 May 202316 minutes to read

Logarithmic axis uses logarithmic scale and it is very useful in visualizing data, when it has numerical values in both lower order of magnitude (eg: 10-6) and higher order of magnitude (eg: 106).

var chartData= [
    { x: new Date(1995, 0, 1), y: 80 }, { x: new Date(1996, 0, 1), y: 200 },
    { x: new Date(1997, 0, 1), y: 400 }, { x: new Date(1998, 0, 1), y: 600 },
    { x: new Date(1999, 0, 1), y: 700 }, { x: new Date(2000, 0, 1), y: 1400 },
    { x: new Date(2001, 0, 1), y: 2000 }, { x: new Date(2002, 0, 1), y: 4000 },
    { x: new Date(2003, 0, 1), y: 6000 }, { x: new Date(2004, 0, 1), y: 8000 },
    { x: new Date(2005, 0, 1), y: 11000 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'DateTime',
        title: 'Years',
        labelFormat: 'y'
    },
    primaryYAxis: {
        // Logarithmic scale in primary X Axis
        valueType: 'Logarithmic',
        title: 'Profit'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        name: 'Product X', type: 'Line'
    }],
    title: 'Product X Growth [1995-2005]'
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Animation</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Note: To use log axis, we need to inject Logarithmic using method Chart.Inject(Logarithmic) and set the valueType of axis to Logarithmic.

Range

Range of an axis, will be calculated automatically based on the provided data, you can also customize the range of an axis using minimum,maximum and interval property of the axis.

var chartData = [
    { x: new Date(1995, 0, 1), y: 80 }, { x: new Date(1996, 0, 1), y: 200 },
    { x: new Date(1997, 0, 1), y: 400 }, { x: new Date(1998, 0, 1), y: 600 },
    { x: new Date(1999, 0, 1), y: 700 }, { x: new Date(2000, 0, 1), y: 1400 },
    { x: new Date(2001, 0, 1), y: 2000 }, { x: new Date(2002, 0, 1), y: 4000 },
    { x: new Date(2003, 0, 1), y: 6000 }, { x: new Date(2004, 0, 1), y: 8000 },
    { x: new Date(2005, 0, 1), y: 11000 }
];
var chart= new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'DateTime',
        title: 'Years',
        labelFormat: 'y'
    },
    primaryYAxis: {
        //Logarithmic scale range in primary X Axis
        valueType: 'Logarithmic',
        title: 'Profit',
        minimum: 100,
        maximum: 10000
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        name: 'Product X', type: 'Line'
    }],
    title: 'Product X Growth [1995-2005]'
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Animation</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Logarithmic Base

Logarithmic base can be customized by using the logBase property of the axis. For example when the logBase is 5, the axis values follows 5-2, 5-1, 50, 51, 52 etc.

var chartData= [
    { x: new Date(1995, 0, 1), y: 80 }, { x: new Date(1996, 0, 1), y: 200 },
    { x: new Date(1997, 0, 1), y: 400 }, { x: new Date(1998, 0, 1), y: 600 },
    { x: new Date(1999, 0, 1), y: 700 }, { x: new Date(2000, 0, 1), y: 1400 },
    { x: new Date(2001, 0, 1), y: 2000 }, { x: new Date(2002, 0, 1), y: 4000 },
    { x: new Date(2003, 0, 1), y: 6000 }, { x: new Date(2004, 0, 1), y: 8000 },
    { x: new Date(2005, 0, 1), y: 11000 }
];
let chart= new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'DateTime',
        title: 'Years',
        labelFormat: 'y'
    },
    primaryYAxis: {
        valueType: 'Logarithmic',
        title: 'Profit',
        // logBase for logarithmic scale
        logBase: 2
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        name: 'Product X', type: 'Line'
    }],
    title: 'Product X Growth [1995-2005]'
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Animation</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Logarithmic Interval

Logarithmic axis interval can be customized by using the interval property of the axis. When the logarithmic base is 10 and logarithmic interval is 2, then the axis labels are placed at an interval of 102. The default value of the interval is 1.

var chartData = [
    { x: new Date(1995, 0, 1), y: 80 }, { x: new Date(1996, 0, 1), y: 200 },
    { x: new Date(1997, 0, 1), y: 400 }, { x: new Date(1998, 0, 1), y: 600 },
    { x: new Date(1999, 0, 1), y: 700 }, { x: new Date(2000, 0, 1), y: 1400 },
    { x: new Date(2001, 0, 1), y: 2000 }, { x: new Date(2002, 0, 1), y: 4000 },
    { x: new Date(2003, 0, 1), y: 6000 }, { x: new Date(2004, 0, 1), y: 8000 },
    { x: new Date(2005, 0, 1), y: 11000 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'DateTime',
        title: 'Years',
        labelFormat: 'y'
    },
    primaryYAxis: {
        //Logarithmic interval in primary X Axis
        valueType: 'Logarithmic',
        title: 'Profit',
        interval: 2
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        name: 'Product X', type: 'Line'
    }],
    title: 'Product X Growth [1995-2005]'
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Animation</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/29.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>