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Radar chart API reference

Example

A dual dataset Radar chart
<script>
    labels = ['John','Fred','Luis','Pete','Gary','Neil','Olga','Terry'];

    new RGraph.Radar({
        id: 'cvs',
        data: [
            [16,18,14,15,14,13,16,18],
            [16,15,14,16,18,16,15,14]
        ],
        options: {
            backgroundCircles: true,
            textSize: 16,
            labels: labels,
            colorsStroke: ['red', 'black'],
            colors: ['rgba(0,0,0,0)'],
            linewidth: 3,
            marginTop: 15,
            marginBottom: 15,
            marginLeft: 85,
            marginRight: 125,
            tooltips: '<b>%{property:labels[%{index}]}\'s results:</b>%{key}',
            tooltipsFormattedKeyLabels: ['2001','2002'],
            tooltipsFormattedKeyColors: ['red', 'black'],
            tooltipsFormattedUnitsPost: '%',
            tooltipsCss: {
                fontSize: '16pt',
                boxShadow: '',
                textAlign: 'left'
            }
        }
    }).draw();
</script>

Properties

You can use these properties to control how the chart appears. You can set them by including them in the options section of the configuration as shown above.

Chart configuration properties

Name: centerx
Description: 
If required, you can position the Radar chart using this instead of the margins. As well as a number, that gives the exact coordinate of the center position of the chart, this can also be a string like this: centerx: '+25' or this: centerx: '-40' which is then used to adjust the calculated coordinate.
Default: null
Name: centery
Description: 
If required, you can position the Radar chart using this instead of the margins. As well as a number, that gives the exact coordinate of the center position of the chart, this can also be a string like this: centery: '+25' or this: centery: '-40' which is then used to adjust the calculated coordinate.
Default: null
Name: radius
Description: 
If required, you can size the Radar chart using this instead of the margins. As well as a number, that gives the exact size of the chart, this can also be a string like this: radius: '+25' or this: radius: '-40' which is then used to adjust the calculated coordinate.
Default: null

Background properties

Name: backgroundGrid
Description: 
Whether the background circles are shown.
Default: true
Name: backgroundGridCount
Description: 
This controls the number of background circles that are shown.
Default: The same as labelsCount
Name: backgroundGridColor
Description: 
This is the color of the background circles.
Default: #ddd
Name: backgroundGridPoly
Description: 
Instead of circles the background lines can be polygons instead. So if you have 4 points you get squares, 5 points pentagons, 6 points hexagons and so on.
Default: true
Name: backgroundGridSpokes
Description: 
This controls how many lines there are that go from the center outwards. This doesn't apply when the poly option is being used.
Default: 24

Margin properties

Name: marginLeft
Description: 
The left margin of the chart, (the margin is where the labels and title are)).
Default: 35
Name: marginRight
Description: 
The right margin of the chart, (the margin is where the labels and title are).
Default: 35
Name: marginTop
Description: 
The top margin of the chart, (the margin is where the labels and title are).
Default: 35
Name: marginBottom
Description: 
The bottom margin of the chart, (the margin is where the labels and title are).
Default: 35

Color properties

Name: colors
Description: 
The colors of the Radar chart.
Default: red
Name: colorsAlpha
Description: 
If set (a number between 0 and 1), this will be used as the alpha value of the colors of the chart.
Default: null
Name: colorsStroke
Description: 
This is the color of the Radar chart. It can be a string or it can be an array of colors (one for each dataset).
Default: #aaa

Fill properties

Name: fillTooltips
Description: 
An array of tooltips that are triggered when you click on the fill of each dataset (not the points).
Default: null
Name: fillMousemove
Description: 
A function that handles the mousemove event when over the fill.
Default: null
Name: fillClick
Description: 
A function that handles the click event when over the fill.
Default: null
Name: fillHighlightFill
Description: 
The color used as the fill for the highlight.
Default: rgba(255,255,255,0.7)
Name: fillHighlightStroke
Description: 
The color used as the stroke for the highlight.
Default: rgba(0,0,0,0)
Name: fillMousemoveRedraw
Description: 
Whether to redraw the chart when the mouse moves. You probably won't need this option.
Default: false

Title properties

Name: title
Description: 
The title of the chart, if any.
Default: null
Name: titleFont
Description: 
The font that the title is rendered in. If not specified the textFont setting is used (usually Arial).
Default: null
Name: titleSize
Description: 
The size of the title. If not specified the size is usually 4pt bigger than the textSize setting.
Default: null
Name: titleBold
Description: 
Whether the title is bold or not.
Default: null
Name: titleItalic
Description: 
Whether the title is italic or not.
Default: null
Name: titleColor
Description: 
The color of the title.
Default: null
Name: titleX
Description: 
To give the exact X coordinate for the title - use this. This can also be a string like this: "-5" - in which case it's converted to a number and added to the calculated coordinate - allowing you to adjust the calculated coordinate.
Default: null
Name: titleY
Description: 
To give the exact Y coordinate for the title - use this. This can also be a string like this: "-5" - in which case it's converted to a number and added to the calculated coordinate - allowing you to adjust the calculated coordinate.
Default: null
Name: titleHalign
Description: 
The horizontal alignment of the title.
Default: center (can change depending on other options)
Name: titleValign
Description: 
The vertical alignment of the title.
Default: center (can change depending on other options)
Name: titleOffsetx
Description: 
You can use this property to adjust the positioning of the title in the horizontal direction (positive values adjust the title to the right and negative values adjust it to the left).
Default:  0
Name: titleOffsety
Description: 
You can use this property to adjust the positioning of the title in the vertical direction (positive values adjust the title downwards and negative values adjust it upwards).
Default:  0
Name: titleSubtitle
Description: 
The subtitle of the chart. If a subtitle is specified the title is moved up to accommodate it. As such you might need to give a larger marginTop value.
Default: null
Name: titleSubtitleSize
Description: 
The size of the font used to render the subtitle.
Default: null
Name: titleSubtitleColor
Description: 
The color of the subtitle.
Default: #aaa
Name: titleSubtitleFont
Description: 
The font used to render the subtitle.
Default: null
Name: titleSubtitleBold
Description: 
Whether the subtitle is bold or not.
Default: null
Name: titleSubtitleItalic
Description: 
Whether the subtitle is italic or not.
Default: null
Name: titleSubtitleOffsetx
Description: 
Use this property to adjust the horizontal position of the subtitle.
Default:  0
Name: titleSubtitleOffsety
Description: 
Use this property to adjust the vertical position of the subtitle.
Default:  0

Labels and text properties

Name: labels
Description: 
The labels to use for the chart. You can also give this option a string if you prefer and use formatted labels.
Default: An empty array
Name: labelsFont
Description: 
The font used to render the labels.
Default: null
Name: labelsSize
Description: 
The size of the labels.
Default: null
Name: labelsColor
Description: 
The color of the labels.
Default: null
Name: labelsBold
Description: 
Whether the labels are bold or not.
Default: null
Name: labelsItalic
Description: 
Whether the labels are italic or not.
Default: null
Name: labelsOffsetRadius
Description: 
The radial offset for the labels that go around the Radar chart.
Default:  0
Name: labelsFormattedDecimals
Description: 
When using formatted labels this is the number of decimals that are applied to the %{value_formatted} macro.
Default:  0
Name: labelsFormattedPoint
Description: 
When using formatted labels this is the decimal point character that's used with the %{value_formatted} macro.
Default: .
Name: labelsFormattedThousand
Description: 
When using formatted labels this is the thousand separator character that's used with the %{value_formatted} macro.
Default: ,
Name: labelsFormattedUnitsPre
Description: 
When using formatted labels these are the units that are prepended to the number with the %{value_formatted} macro.
Default: (an empty string)
Name: labelsFormattedUnitsPost
Description: 
When using formatted labels these are the units that are appended to the number with the %{value_formatted} macro.
Default: (an empty string)
Name: labelsClass
Description: 
This property allows you to add your own css class to the labels which you can then use for styling purposes or to make retrieving the span tags easier (the dom elements). If you inspect the labels in your browser's javascript console (you will first need to enable the textAccessiblePointerevents property) you will be able to see the other css classes that are assigned to the labels.
Default: [none]
Name: labelsAxes
Description: 
This controls the axes that show the scale labels. Each letter stands for the appropriate axis (North, South, East and West).
Default:  (An empty string)
Name: labelsAxesFont
Description: 
The font used by the labels.
Default: null
Name: labelsAxesSize
Description: 
The size of the labels.
Default: null
Name: labelsAxesColor
Description: 
The color of the labels.
Default: null
Name: labelsAxesBold
Description: 
This controls whether the axis labels are bold or not.
Default: null
Name: labelsAxesItalic
Description: 
This controls whether the axis labels are italic or not.
Default: null
Name: labelsAxesCount
Description: 
This controls how many scale labels are displayed.
Default: white
Name: labelsAxesOffsetx
Description: 
The horizontal offset that gets applied to the axes labels.
Default:  0
Name: labelsAxesOffsety
Description: 
The vertical offset that gets applied to the axes labels.
Default:  0
Name: textFont
Description: 
The font used to render the text.
Default: Arial, Verdana, sans-serif
Name: textColor
Description: 
The color of the labels.
Default: black
Name: textSize
Description: 
The size of the text.
Default: 12
Name: textBold
Description: 
Whether the text is bold or not.
Default: false
Name: textItalic
Description: 
Whether the text is italic or not.
Default: false
Name: textAccessible
Description: 
A new feature in 2016 that allows you to use dom text in place of canvas text. It makes for a much higher quality text that you can also select if desired (for copy/paste operations). It won't fit all situations and you can read more about the DOM text feature here. A good way to control borders/margins/padding etc is not to set them on the canvas but to wrap the canvas in a div and set them on that like this:
<div style="margin-left: 50px; display: inline-block">
    <canvas id="cvs" width="650" height="250"></canvas>
</div>
Default: false
Name: textAccessibleOverflow
Description: 
This can be visible or hidden and it controls whether the text is clipped to the edges of the canvas. It defaults to be visible and means you can set small margins if you wish.
Default: visible
Name: textAccessiblePointerevents
Description: 
This controls whether the dom text responds to mouse-based events or not (it sets the pointer-events css property to none).
Default: true
Name: text
Description: 
This allows you to add custom text to your chart if you want to. There's a dedicated page that describes this option here.
Default: null

Scale properties

Name: scaleMax
Description: 
The optional maximum scale value. If not specified then it will be calculated.
Default: null (It's calculated)
Name: scaleRound
Description: 
Whether to round the maximum scale value up or not. This will produce slightly better scales in some instances.
Default: null
Name: scalePoint
Description: 
The character that's used as the decimal point.
Default: .
Name: scaleThousand
Description: 
The character that's used as the thousand separator.
Default: ,
Name: scaleDecimals
Description: 
This stipulates how many decimal places there are.
Default:  0
Name: scaleUnitsPre
Description: 
These units are prepended to the scale numbers.
Default: [an empty string]
Name: scaleUnitsPost
Description: 
These units are appended to the scale numbers.
Default: [an empty string]

Axis properties

Name: axesColor
Description: 
This is the color of the axes.
Default: black
Name: axesLinewidth
Description: 
This is the linewidth of the axes.
Default: 1

Key properties

The key properties are documented on the key documentation page.

Interactive features properties

Name: contextmenu
Description: 
An array of context menu items. More information about context menus is here.
Default: An empty array
Name: annotatable
Description: 
Whether annotations are enabled for the chart (ie you can draw on the chart interactively.
Default: false
Name: annotatableColor
Description: 
If you do not allow the use of the palette, then this will be the only color allowed for annotations.
Default: black
Name: annotatableLinewidth
Description: 
This is the linewidth of the annotations.
Default: 1
Name: tooltips
Description: 
A numerically indexed array of tooltips that are shown when a point is hovered over. These can contain html.
Default: []
Name: tooltipsEvent
Description: 
This is the event that triggers the tooltips. It can be either click or mousemove.
Default: mousemove
Name: tooltipsEffect
Description: 
The effect used for showing tooltips. Possible values are slide fade or none.
Default: slide
Name: tooltipsOverride
Description: 
If you wish to handle showing tooltips yourself, this should be a function object which does just that. There's more information on the tooltips documentation page.
Default: null
Name: tooltipsFormattedPoint
Description: 
When using formatted tooltip strings this is used as the point when using the %{value_formatted} option.
Default: .
Name: tooltipsFormattedThousand
Description: 
When using formatted tooltip strings this is used as the thousand separator when using the %{value_formatted} option.
Default: ,
Name: tooltipsFormattedDecimals
Description: 
When using formatted tooltip strings this specifies the number of decimals when using the %{value_formatted} option.
Default:  0
Name: tooltipsFormattedUnitsPre
Description: 
When using formatted tooltip strings these units are prepended to the number when using the %{value_formatted} option.
Default: (an empty string)
Name: tooltipsFormattedUnitsPost
Description: 
When using formatted tooltip strings these units are appended to the number when using the %{value_formatted} option.
Default: (an empty string)
Name: tooltipsFormattedKeyColors
Description: 
When using formatted tooltip strings you can give specific colors for the %{key} option to use.
Default: null
Name: tooltipsFormattedKeyColorsShape
Description: 
This is the shape that's used in the tooltip key. It can be square or circle
Default: square
Name: tooltipsFormattedKeyColorsCss
Description: 
By using this property you can add css values to the key color shape that appears in the tooltip key. Note the property name is "color" and not "colors" like previous properties. It should be an object of css properties like this:
tooltipsFormattedKeyColorsCss : {
    border: "1px solid #ddd";
}
Default: null
Name: tooltipsFormattedKeyLabels
Description: 
When using formatted tooltip strings these are the labels that are displayed.
Default: [] (an empty array)
Name: tooltipsFormattedListType
Description: 
With this property you can switch between an unordered list (the default) and an ordered list. Possible values are ul and ol.
Default: ul
Name: tooltipsFormattedListItems
Description: 
This should be a two-dimension array of the list items that are to be shown for all of the tooltips. An example of this property is:
tooltipsFormattedListItems: [
    ['Bill','Jerry','Berty'], // First tooltip
    ['Gill','Carrie','Lucy'], // Second tooltip
    ['Pob','Nobby','Hilda']   // Third tooltip
]
You can use css to style this list - for example:
.RGraph_tooltip ul#rgraph_formatted_tooltips_list li {
    text-align: left;
    color: yellow;
}
Default: null
Name: tooltipsFormattedTableHeaders
Description: 
When showing a table in the tooltips this can be an array of headers for the table. These are added to the tooltip using th tags.
Default: null
Name: tooltipsFormattedTableData
Description: 
This is the data that is added to the table. This is a 3-dimensional array so it's easy to make a mistake. See the example, copy the code from it and then modify it suit. You'll create fewer bugs this way.
Default: null)
Name: tooltipsPointer
Description: 
By default the tooltips have a small triangular pointer that points to the shape that was clicked on. You can turn this off with this property.
Default: true
Name: tooltipsPointerCss
Description: 
If you want any css values applied to the tooltips pointer (a css border, for example) then specify an object containing those values to this property. For example:
tooltipsPointerCss: {
    borderLeft: 'gray 2px solid',
    borderBottom: 'gray 2px solid'
}
Default: null
Name: tooltipsPointerOffsetx
Description: 
This allows you to adjust the vertical position of the tooltips pointer.
Default:  0
Name: tooltipsPointerOffsety
Description: 
This allows you to adjust the vertical position of the tooltips pointer (for example, if you add a border you may need to move it down slightly).
Default:  0
Name: tooltipsPositionStatic
Description: 
The new default (as of August 2020) is for tooltips to be positioned statically and not be dependent on the mouse position. If you don't want this for whatever reason, you can disable it with this setting. When you set it to false tooltips are positioned next to the mouse pointer.
Default: true
Name: tooltipsCss
Description: 
If you want to specify some css that gets applied to all of the tooltips, but don't want to use the RGraph.tooltips.style object (which gets applied to all of the tooltips on the page for every chart) you can use this property to give some per-object css for the tooltips. These are css styles that get applied to all of the tooltips for the specific object only. It should look like this:
tooltipsCss: {
    fontFamily: 'Verdana',
    fontSize: '20pt'
}
Default: null
Name: tooltipsCssClass
Description: 
This is the name of the css class the chart uses.
Default: RGraph_tooltip
Name: tooltipsOffsetx
Description: 
This property allows you to shift the tooltips left or right.
Default:  0
Name: tooltipsOffsety
Description: 
This property allows you to shift the tooltips up or down.
Default:  0
Name: tooltipsHotspotIgnore
Description: 
This can be a number of things and can be used to ignore certain tooltip hotspots - which can allow charts to the rear to be clickable. There's an example of this in the download archive called pie-tooltipshotspotignore.html. You can use the transparent color to allow the rear chart to be seen in such a case. It can be:
  • A single boolean value (ie true or false) to enable or disable all of the hotspots - true means the hotspot will be ignored
  • A single number (the zero-indexed number corresponding to the hotspot to ignore)
  • An array of numbers (the numbers are the indexes of hotspots to ignore)
  • An array of boolean true or false values - the position of these values correspond to the index(es) of the segments to ignore (for example [false, false, true, false, false] - true means the corresponding hotspot will be ignored)
Default: null

Miscellaneous properties

Name: highlightStyle
Description: 
By default this is null but you can set it to a function which is called to do the chart highlighting. It's passed the shape object as an argument. As of version 5.23 you can also set this to invert as well. If you do this on a dark background you may find that you need to change the highlightFill color setting as well.
Default: null
Name: highlightLinewidth
Description: 
If you use tooltips, this controls the color of the highlight stroke.
Default: gray
Name: highlightStroke
Description: 
If you use tooltips, this controls the color of the highlight stroke.
Default: gray
Name: highlightFill
Description: 
If you use tooltips, this controls the color of the highlight fill.
Default: white
Name: highlightPointRadius
Description: 
This controls the size of the highlight when tooltips are used.
Default: 2
Name: tickmarks
Description: 
This adds tickmarks to the Radar chart.
Default: true
Name: tickmarksRadius
Description: 
The radius of the tickmarks.
Default: 3
Name: tickmarksStroke
Description: 
The color of the stroke of the tickmark. By default, this is the same as the color of the line.
Default: null
Name: tickmarksFill
Description: 
The color that the tickmark is filled with.
Default: white
Name: tickmarksLinewidth
Description: 
The linewidth used for the tickmarks. By default this is the same as the linewidth of the chart.
Default: null
Name: linewidth
Description: 
The width of the outline.
Default: 1
Name: circle
Description: 
What value to draw a circle at. Defaults to zero (off). You could use this to represent a threshold of some sort.
Default:  0
Name: circleFill
Description: 
What color to fill the circle with.
Default: red
Name: circleStroke
Description: 
What color to stroke (ie The outline) the circle with.
Default: black
Name: accumulative
Description: 
If set to true this will produce a stacked Radar chart. Obviously, you must have two or more data sets, and also the data sets must have the same number of data points.
Default: false
Name: clearto
Description: 
This is used in animations and effects as the default color to use when the canvas.
Default: null
Name: responsive
Description: 
This option is new to the July 2023 release (v6.13) and allows you to inline the responsive configuration instead of appending it on to the end of the object it as a function. The documentation and demo pages have been updated to use this new option. You can read more about the responsive feature by reading the responsive configuration page.
Default: null

Methods

obj.get(name)

An accessor that you can use to retrieve the values of properties.


obj.set(name, value)

An accessor that you can use to set the values of properties.


obj.getShape(event)
This method makes it easy to get hold of which segment has been clicked on or hovered over. It returns an object which has the following indexes available:
object The chart object
x This is the X coordinate for the point.
y This is the Y coordinate for the point.
dataset The zero-indexed dataset index.
index The zero-indexed index of the relevant point in the dataset.
sequentialIndex The zero-indexed sequential index of the point on the chart.
tooltip If a tooltip is associated with this segment this will be it. id: strings are expanded for you (where the tooltip text is retrieved from the html tag with the matching ID).
<script>
    radar.canvas.onclick = function (e)
    {
        RGraph.redraw();
    
        var canvas  = e.target,
            obj     = canvas.__object__,
            shape   = obj.getShape(e);

        if (shape) {
            
            var x = shape.x,
                y = shape.y;

            obj.path(
                'b a % % 5 0 6.29 false s black f red',
                x, y
            );
        }
    }
</script>

obj.getRadius(value)

This function returns the distance from the center for a particular value - the radius of an imaginary circle in effect.


obj.getAngle(numitems, index)

The Radar chart values are spaced equally around the chart (in terms of their angles). So the angle for a particular data point can easily be calculated. This method makes it even easier. Simply pass it the total number of data points that you have and the zero-indexed number of the one you want and this will return you an appropriate angle. eg for the fourth item out of 8 total data points you would do this: obj.getAngle(8, 3);


obj.on(event, function)

This method can be used to set an event listener on an object. It operates similarly to the jquery on function. The first argument is the event that you wish to attach to and the second is the handler function. For example:

obj.on('draw', function (obj)
{
    // Put your event code here
});

The function is useful if you use method chaining when creating your charts:

new RGraph.Radar({
    id: 'cvs',
    data: [8,6,4,3,8,7,4,9],
    options: {
    }
}).on('draw', function (obj)
{
    // Put your draw event code here

}).on('click', function (e, shape)
{
    // Put your click event code here
}).draw()

obj.exec(function)

The exec function is documented here.


obj.responsive(configuration)

The responsive function helps your charts respond to different browser window sizes and screen resolutions. For example, for smaller screens, you might want to have angled labels or show shorter versions of them completely.

Update: There is now the responsive configuration option available to you and this is now the preferred method of configuration.

The responsive function and configuration option are documented on their own page here.

obj.highlightDataset(dataset_index)

If you're using the fillClick or the fillMousemove options then you may want to make use of this function - which will highlight a dataset for you. You pass it the index of the dataset (0 for the first dataset, 1 for the second etc) and this will add highlighting for you. It uses the highlightFill and highlightStroke options for the colors.


The coords and coords2 arrays

The X/Y coordinates for the points on the Radar chart are held in two different ways. The obj.coords array is one long array containing all of the coordinates for all of the datasets. The obj.coords2 on the other hand holds the same coordinates but in a multi-dimensional way - so, keeping in mind that the numbering starts at zero, obj.coords2[1][3] refers to the fourth point in the second dataset.

Highlighting data series

New in November 2012 is the ability to highlight a data series. This allows you to associate a function to run when a data series is clicked or hovered over. In addition to being able to run a function, you can also specify a set of tooltips that are shown when the datasets are clicked on or hovered over. These tooltips can be shown using the mousemove or the click events. If you need it - there is an obj.HighlightDataset(dataset) method which you can use to highlight a specific dataset. The appropriate properties and their default values are:


<script>
    new RGraph.Radar({
        id: 'cvs',
        data: [
            [4,8,6,5,3,5,4,6,8,7],
            [4,2,3,5,1,6,5,4,5,3]
        ],
        options: {
            marginBottom: 35,
            labels: ['Bob','Richard','Luis','Pete','Gemma','Karen','Lee','Olga','Kevin','Luis'],
            colors: ['red', 'green'],
            colorsAlpha: 0.4,
            axesColor: 'rgba(0,0,0,0)',
            accumulative: true,
            backgroundCirclesPoly: true,
            colorsStroke: 'rgba(0,0,0,0)',
            textSize: 10,
            fillTooltips: ['The first datasets tooltip', 'The second datasets tooltip'])
        }
    }).draw();
</script>

Events

RGraph supports custom events that allow you to easily add interactivity to your charts if required. The following events are available:

For example:
new RGraph.Radar({
    id: 'cvs',
    data: [4,8,6,3,5,8,9],
    options: {
    }
}).on('draw', function (obj)
{
    console.log('The draw event has fired');
    
}).draw();

Effects

These effects are available and can be used instead of the draw function. There are also generic effects available which you can see here: Generic effects and transitions
<script>
    // Optional callback function that's called when the effect is complete
    function myCallback (obj)
    {
        // ...
    }

    new RGraph.Radar({
        id: 'cvs',
        data: [8,7,6,8,4,9,5,9,8],
        options: {
            marginLeft: 35
        }
    }).trace({frames: 60}, myCallback)
    // .grow({frames: 60}, myCallback)
</script>