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RGraph is a JavaScript charts library based on HTML5 SVG and canvas. RGraph is mature (over 15 years old) and has a wealth of features making it an ideal choice to use for showing charts on your website.

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Get the latest version of RGraph (version 6.18, 1st June 2024) from the download page. You can read the changelog here. There's also older versions available, minified files and links to cdnjs.com hosted libraries.

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License
RGraph can be used for free under the GPL or if that doesn't suit your situation there's an inexpensive (£129) commercial license available.

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Radial Scatter chart API reference

Example

A basic RScatter chart
<script>
    tooltip = '%{key}';

    new RGraph.RScatter({
        id: 'cvs',
        data: [
            [ [15,53,'red',tooltip], [45,63,'red',tooltip], [48,45,'red',tooltip], [52,38,'red',tooltip], [51,61,'red',tooltip] ],
            [ [270,45, 'blue',tooltip], [270,55, 'red',tooltip] ]
        ],
        options: {
            tooltipsFormattedKeyLabels: ['John','Molly','Pete','Olga','Luis','Kevin','Julie'],
            tooltipsCss: {
                fontSize: '16pt',
                boxShadow: '',
                textAlign: 'left'
            },
            labels: ['NE','E','SE','S','SW','W','NW','N'],
            labelsPosition: 'edge',
            marginLeft: 35,
            marginRight: 35,
            labelsAxesSize: 8
        }
    }).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 Radial Scatter 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 Radial Scatter 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 Radial Scatter 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 grid is drawn.
Default: true
Name: backgroundGridColor
Description: 
The color of the background grid.
Default: #ccc
Name: backgroundGridRadials
Description: 
Whether the lines that emanate from center outwards are drawn.
Default: true
Name: backgroundGridRadialsCount
Description: 
The number of diagonal lines in the background grid.
Default: null
Name: backgroundGridCircles
Description: 
Whether the background grid circles (or angular lines) are drawn.
Default: true
Name: backgroundGridCirclesCount
Description: 
How many circular/angular grid lines are drawn.
Default: 5
Name: backgroundGridLinewidth
Description: 
The linewidth of the background grid.
Default: 1
Name: backgroundColor
Description: 
The background color of the chart. You can use gradients here if you wish.
Default: none

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: colorsDefault
Description: 
The default color that's used for the tickmarks.
Default: black

Tickmark properties

Name: tickmarksStyle
Description: 
This property was formerly called tickmarks and dictates how the tickmarks are drawn It defaults to cross but can also be circle square diamond or plus
Default: 
Name: tickmarksSize
Description: 
This determines the size of the tickmarks.
Default: 3

Labels and text properties

Name: textAccessible
Description: 
A new feature in 2016 that allows you to use dom text in place of canvas text. It makes for 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: textColor
Description: 
The color of the text on the chart.
Default: black
Name: textSize
Description: 
The size of the text on the chart.
Default: 12
Name: textFont
Description: 
The font used to render the text on the chart.
Default: Arial, Verdana, sans-serif
Name: textItalic
Description: 
Whether the text on the chart is italic or not.
Default: false
Name: textBold
Description: 
Whether the text on the chart is bold or not.
Default: false
Name: labels
Description: 
The circular labels for the chart. You can also give this option a string if you prefer and use formatted labels.
Default: none
Name: labelsOffsetRadius
Description: 
To offset the labels either away from or towards the Rose chart then this is the property to use for that.
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: labelsFont
Description: 
The font used by the circular labels.
Default: null (same as textFont)
Name: labelsSize
Description: 
The size of the circular labels.
Default: null (same as textSize)
Name: labelsColor
Description: 
The color of the circular labels.
Default: null (same as textColor)
Name: labelsBold
Description: 
Whether the circular labels are bold or not.
Default: null (same as textBold)
Name: labelsItalic
Description: 
Whether the circular labels are italic or not.
Default: null (same as textItalic)
Name: labelsPosition
Description: 
This can be either center or edge and determines the position of the labels.
Default: center
Name: labelsAxes
Description: 
This controls the axes that show the scale labels. It should be a combination of 4 letters: n, e, s, w Each letter stands for the appropriate axis (North, South, East and West).
Default: n
Name: labelsAxesBackground
Description: 
This is the color of the background for the labels.
Default: rgba(255,255,255,0.7)
Name: labelsAxesFont
Description: 
The font used for the labels on the axes.
Default: null
Name: labelsAxesSize
Description: 
The size of the labels on the axes.
Default: null
Name: labelsAxesColor
Description: 
The color of the labels on the axes.
Default: null
Name: labelsAxesBold
Description: 
Whether the labels on the axes are bold or not.
Default: null
Name: labelsAxesItalic
Description: 
Whether the labels on the axes are italic or not.
Default: null
Name: labelsAxesOffsetx
Description: 
This allows you finer-grained control in the horizontal direction over the text positioning if you need it.
Default:  0
Name: labelsAxesOffsety
Description: 
This allows you finer-grained control in the vertical direction over the text positioning if you need it.
Default:  0
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

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

Key properties

The key properties are documented on the key documentation page.

Scale properties

Name: scaleMax
Description: 
The maximum value of the scale on the chart. By default this is generated based on the data that you supply.
Default: null
Name: scaleUnitsPre
Description: 
Units that are prepended to the number.
Default: .
Name: scaleUnitsPost
Description: 
Units that are appended to the number.
Default: .
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: scaleZerostart
Description: 
If true then the zero label will be shown (this is the default now).
Default: true

Interactive features properties

Name: contextmenu
Description: 
An array of context menu items. More information about context menus is here.
Default: [] (An empty array)
Name: tooltips
Description: 
A numerically indexed array of tooltips that are shown when a bar is clicked. These can contain html.
Default: An empty array
Name: tooltipsEffect
Description: 
The effect used for showing tooltips. Possible values are slide fade or none.
Default: slide
Name: tooltipsEvent
Description: 
This is the event that triggers the tooltips. It can be either click or mousemove.
Default: click
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 in 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
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

Axes properties

Name: axesColor
Description: 
The color of the axes.
Default: rgba(0,0,0,0)

Line properties

Name: line
Description: 
If true the points will be connected by a line.
Default: false
Name: lineClose
Description: 
If true then the line will be closed (ie last point connects back to the first point).
Default: false
Name: lineLinewidth
Description: 
The linewidth of the line.
Default: 1
Name: lineColors
Description: 
The color(s) of the line(s).
Default: ['black']
Name: lineShadow
Description: 
Whether the lines have a shadow.
Default: false
Name: lineShadowColor
Description: 
The color of the shadow.
Default: black
Name: lineShadowOffsetx
Description: 
The horizontal offset of the shadow.
Default: 3
Name: lineShadowOffsety
Description: 
The vertical offset of the shadow.
Default: 3
Name: lineShadowBlur
Description: 
The severity of the shadow blurring effect.
Default: 2

Miscellaneous properties

Name: highlightStyle
Description: 
By default this is null but you can set it to a function if you wish so that function is called to do the chart highlighting. Its 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: highlightSize
Description: 
The size of the highlight that gets drawn over the tickmark. If this property is not set then the highlight will be approximately the same size as the tooltip.
Default: null
Name: highlightFill
Description: 
The fill color of the tooltip.
Default: rgba(255,255,255,0.7)
Name: highlightStroke
Description: 
The stroke color of the tooltip.
Default: transparent
Name: clearto
Description: 
This is used in animations and effects as the default color to use when clearing the canvas.
Default: null
Name: segmentHighlight
Description: 
If you wish you can have segments of the chart highlight as you move the mouse around.
Default: false
Name: segmentHighlightCount
Description: 
The number of segments by default corresponds to the number of "radials" that the background grid has but using this property you can set it explicitly.
Default: null
Name: segmentHighlightFill
Description: 
The fill color of the highlight.
Default: rgba(0,255,0,0.5)
Name: segmentHighlightStroke
Description: 
The stroke color of the highlight.
Default: rgba(0,0,0,0)
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 point 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 of the point.
y This is the Y coordinate of the point.
dataset This is the zero-indexed index of the dataset that the point belongs to.
index The zero-indexed index of the point on the chart.
sequentialIndex This is the zero-indexed sequential index of the point on the chart.
tooltip If a tooltip is associated with this point 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>
    rscatter.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;

            // Path a circle that indicates the point
            obj.path(
                'b a % % 5 0 6.29 false s red f red',
                x, y
            );
        }
    }
</script>

obj.getRadius(value)

This method can be used to get an appropriate radius of a point based on the scale. This is useful when working out how far away from the center a point should be. In a set of coordinates, the first value is the rotational value in degrees - it can be 0-360.


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:

var obj = new RGraph.RScatter({
    id: 'cvs',
    data: [[45,36],[48,68],[66,56],[95,35],[120,45],[155,65]],
    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.

The coordinates properties

There are two coordinates arrays available on the RScatter chart: the obj.coords array and the obj.coords2 array.

Events

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

For example:
var obj = new RGraph.RScatter({
    id: 'cvs',
    data: [[45,36],[48,68],[66,56],[95,35],[120,45],[155,65]],
    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>
    //
    // The optional callback function that's called when the effect is complete
    //
    function myCallback (obj)
    {
        // ...
    }

    rscatter = new RGraph.RScatter({
        id: 'cvs',
        data: [ [15,53,'red',tooltip], [45,63,'red',tooltip], [48,45,'red',tooltip], [52,38,'red',tooltip], [51,61,'red',tooltip] ],
        options: {
            labels: ['NE','E','SE','S','SW','W','NW','N'],
            labelsPosition: 'edge',
            marginLeft: 35,
            marginRight: 35,
            labelsAxesSize: 8
        }
    }).explode({frames: 60}, myCallback);
</script>