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Charts

Screenshot of the Charts widget The Charts module provides a JavaScript API for visualizing data in a variety of formats across a browser test baseline. Based on device and browser capabilities, Charts leverages SVG, HTML Canvas and VML to render its graphical elements.

The Charts module features a Chart class that allows you to easily create a chart from a set of data. Chart extends Widget and includes configurable attributes that enable you to customize a Chart. Currently, the Chart widget can be used to create different variations and combinations of line, marker, area, spline, column, bar and pie charts.

Getting Started

To include the source files for Charts and its dependencies, first load the YUI seed file if you haven't already loaded it.

<script src="http://yui.yahooapis.com/3.8.0/build/yui/yui-min.js"></script>

Next, create a new YUI instance for your application and populate it with the modules you need by specifying them as arguments to the YUI().use() method. YUI will automatically load any dependencies required by the modules you specify.

<script>
// Create a new YUI instance and populate it with the required modules.
YUI().use('charts', function (Y) {
    // Charts is available and ready for use. Add implementation
    // code here.
});
</script>

For more information on creating YUI instances and on the use() method, see the documentation for the YUI Global Object.

Using the charts widget

This section describes how to use the charts widget in further detail. It contains these subsections:

Instantiating A Chart

All you need to instantiate a chart is

  1. A div container to render the chart.
  2. An array to provide data for the chart.

CSS

#mychart {
    width: 600px;
    height: 400px;
}

HTML

<div id="mychart"></div>

JavaScript

// Data for the chart
var myDataValues = [
    {category:"5/1/2010", values:2000},
    {category:"5/2/2010", values:50},
    {category:"5/3/2010", values:400},
    {category:"5/4/2010", values:200},
    {category:"5/5/2010", values:5000}
];

// Instantiate and render the chart
var mychart = new Y.Chart({
    dataProvider: myDataValues,
    render: "#mychart"
});

By default, Chart creates a graph with lines and markers. This can be changed through the type attribute. Available values are listed below:

Type Description
area Visualizes quantitative data with a fill between an axis and relevant data points.
areaspline An Area Chart in which data points are connected by a curve.
bar Visualizes bars positioned vertically along a category or time axis. The bars' lengths are proportional to the values they represent along a horizontal axis.
column Visualizes bars positioned vertically along a category or time axis. The bars' lengths are proportional to the values they represent along a horizontal axis.
combo Combination of line, marker and area chart. By default, there is no area fill. This is the default type for a Chart.
combospline A combo chart in which the data points are connected by a curve.
line Visualizes quantitative data on a graph by connecting relevant data points.
markerseries Visualizes quantitative data by plotting relevant data points on a graph.
pie A circular chart divided into wedges which represent data as a percentage of a whole.
spline Visualizes quantitative data on a graph by connecting relevant data points with a curve.

Chart Application

The Chart class acts as a facade for two underlying application classes:

CartesianChart
An application used to render multiple series to a graph with x and y axes. Many series can be rendered in a CartesianChart.
PieChart
An application used to render Pie Charts.

When Chart is instantiated, the type attribute determines which class instance will be returned. A value of pie will return an instance of PieChart. All other values will return an instance of CartesianChart. For the most part, this is a distinction that only occurs under the hood. As a developer, this can be viewed as a single API.

Attributes

The Chart widget adds the following key attributes, in addition to the attributes provided by the base Widget class:

Property Type Description
axes Object Axes to appear in the chart. This can be an object of axis instances or object literals used to construct the appropriate axes.
categoryAxis Axis Reference to the chart's category axis.
categoryAxisName String Indicates the key value used to identify a category axis in the axes hash. If not specified, the categoryKey attribute value will be used.
categoryKey String The key value used for the chart's category axis. The default value is category.
categoryType String Indicates whether to use a CategoryAxis or TimeAxis for the Chart instance's category axis. The default value is category.
dataProvider Array Array of data used to construct the chart.
direction String Direction of chart's category axis when there is no series collection specified. Charts can be horizontal or vertical. When the chart type is column, the chart is horizontal. When the chart type is bar, the chart is vertical.
horizontalGridlines Gridlines Reference to the horizontalGridlines for a cartesian chart.
interactionType String Indicates the the Chart instance will fire marker or planar events. The default value is marker.
legend Object Provides a legend for a Chart.
seriesCollection ArrayCollection of series to appear on the chart. This can be an array of Series instances or object literals used to construct the appropriate series.
seriesKeys Array A collection of keys that map to the series axes. If no keys are set, they will be generated automatically depending on the data structure passed into the chart.
showAreaFill Boolean Indicates whether or not an area is filled in a combo chart.
showLines Boolean Indicates whether to display lines in a combo chart.
showMarkers Boolean Indicates whether to display markers in a combo chart.
stacked Boolean Indicates whether or not the chart is stacked.
styles Object properties for the chart.
tooltip Object Reference to the default tooltip available for the chart.
type String Indicates the default series type for the chart. The default value is combo
valueAxisName String Indicates the key value used to identify the default value axis.
verticalGridlines Gridlines Reference to the verticalGridlines for a cartesian chart.

The dataProvider Attribute

The only required attributes for instantiating a Chart instance are dataProvider and render. The render attribute can be included in the configuration argument or called explicitly after instantiation.

mychart.render("#mychart");

The Chart widget requires an array for its source of data. The Chart widget will accept an array of object literals or arrays. When an array of arrays is received, the values in the first index will be used for the category axis and all subsequent indices will be used for the value axis/axes. When an array of object literals is received, all records with a key matching the categoryKey attribute will be used for the category axis with all other records used for the value axis/axes.

Multi-dimensional Array

var myDataValues = [
    ["5/1/2010", "5/2/2010", "5/3/2010", "5/4/2010", "5/5/2010"],
    [2000, 50, 400, 200, 5000]
];

Object Literal Array

var myDataValues = [
    {category:"5/1/2010", values:2000},
    {category:"5/2/2010", values:50},
    {category:"5/3/2010", values:400},
    {category:"5/4/2010", values:200},
    {category:"5/5/2010", values:5000}
];

The underlying structure of the dataProvider is an array of object literals. If a Chart receives a multi-dimensional array for its dataProvider, it will convert the array to an array of object literals.

Using the tooltip Attribute

The Chart class comes with a built-in simple tooltip. This tooltip can be customized or disabled with the tooltip attribute which contains the following properties:

PropertyTypeDescription
hideEventString/ArrayEvent that hides the tooltip. This allows you to specify which mouse event(s) hides the tooltip. You can also pass this an array of events and each event in the array will hide the tooltip. The default value is mouseout.
markerEventHandlerFunctionDisplays and hides a tooltip based on marker events.
markerLabelFunctionFunctionReference to the function used to format a marker event triggered tooltip's text. The markerLabelFunction has the following arguments:
categoryItem
An object containing the following:
axis
The axis that the category is bound to
displayName
The display name set to the category (defaults to key if not provided)
key
The key of the category
value
The value of the category
valueItem
An object containing the following:
axis
The axis that the item's series is bound to
displayName
The display name of the series (defaults to key if not provided)
key
The key for the series
value
The value for the series item
itemIndex
The index of the item within its series.
series
The series that the item belongs to
seriesIndex
The index of the series in the seriesCollection
The method returns an HTMLElement which is written into the DOM using appendChild. If you override this method and choose to return an html string, you will also need to override the tooltip's setTextFunction method to accept an html string.

*NOTE: Previous to 3.5.0, this method used innerHTML. The functionality was changed to prevent potential security vectors. If you have current implementations in which your custom markerLabelFunction is dependent on innerHTML to format your text. You will need to either change them to work with appendChild or update the tooltip's setFunction method to accept an html string.

tooltip: {
    setTextFunction: function(textField, val) {
        textField.setHTML(val);
    }
}
If you use such a strategy, please ensure your content is safe.

nodeHTMLElementReference (read-only) to the actual dom node of the tooltip.
planarEventHandlerFunctionDisplays and hides a tooltip based on planar events.
planarLabelFunctionFunctionReference to the function used to format a planar event triggered tooltip's text. The planarLabelFunction has the following arguments:
categoryAxis
Reference to the categoryAxis of the chart.
valueItems
Array of objects for each series that has a data point in the coordinate plane of the event. Each object contains the following data:
axis
The value axis of the series.
key
The key for the series.
value
The value for the series item.
displayName
The display name of the series. (defaults to key if not provided)
index
The index of the item within its series.
seriesArray
Array of series instances for each value item.
seriesIndex
The index of the series in the seriesCollection.
The method returns an HTMLElement which is written into the DOM using appendChild. If you override this method and choose to return an html string, you will also need to override the tooltip's setTextFunction method to accept an html string.

*NOTE: Previous to 3.5.0, this method used innerHTML. The functionality was changed to prevent potential security vectors. If you have current implementations in which your custom planarLabelFunction is dependent on innerHTML to format your text. You will need to either change them to work with appendChild or update the tooltip's setFunction method to accept an html string.

tooltip: {
    setTextFunction: function(textField, val) {
        textField.setHTML(val);
    }
}
If you use such a strategy, please ensure your content is safe.

setTextFunctionFunctionMethod that writes content returned from planarLabelFunction or markerLabelFunction into the the tooltip node. has the following signature:
label
The HTMLElement that the content is to be added.
val
The content to be rendered into tooltip. This can be a String or HTMLElement. If an HTML string is used, it will be rendered as a string.
showBooleanIndicates whether to show a tooltip.
showEventStringEvent that triggers the tooltip. This allows you to specify which mouse event will cause the tooltip to display. The default value is mouseover
stylesObjectHash of CSS styles that are applied to the tooltip's node.

Styling a CartesianChart with the styles Attribute

The styles attribute can be used to update the properties of different chart components in a CartesianChart.

PropertyTypeDescription
axesObjectAn object containing references to the styles attribute for each Axis instance in the chart.
graphObjectA reference to the styles attribute of the chart applications's Graph.
seriesObjectAn object containing references to the styles attribute for each CartesianSeries instance in the chart.

Using the axes Attribute

The axes attribute allows you to specify axes to be used in the chart. The axes attribute contains a hash of either Axis instances or object literals containing information that the Chart will use to create axes. The most common use case is to use object literals. Below are the attributes available:

PropertyTypeDescription
alwaysShowZeroBooleanEnsures that zero appears on a NumericAxis when minimum and maximum are not explicitly set.
keysArrayAn array keys used to bind data from the dataProvider to the axis.
labelFormatObjectTemplate for formatting labels. Used by labelFunction in NumericAxis and TimeAxis instances. For TimeAxis instances the labelFormat is an STRFTime string. For NumericAxis instances the labelFormat is an object literal containing the following properties:
  • prefix
  • thousandsSeparator
  • decimalSeparator
  • decimalPlaces
  • suffix
labelFunctionFunctionFunction used to format axis labels for display. The return value is added to the Axis with appendChild.

*NOTE: Previous to 3.5.0, this method used innerHTML. The functionality was changed to prevent potential security vectors. If you have current implementations in which your custom labelFunction is dependent on innerHTML to format your text. You will need to either change them to work with appendChild or update the Axis' appendLabelFunction method to accept an html string.

appendLabelFunction: function(textField, val) {
    textField.innerHTML = val;
}
If you use such a strategy, please ensure your content is safe.

appendLabelFunctionFunctionFunction used to add the output of the labelFunction to the Axis using appendChild. This attribute can be overridden as needed.
titleStringOptional attribute that allows for specification of an axis title. The value of this attribute is added to the Axis with appendChild.

*NOTE: Previous to 3.5.0, this attribute was added to the DOM using innerHTML. The functionality was changed to prevent potential security vectors. If you have current implementations in which the value of the title attribute is dependent on innerHTML to format your text. You will need to either change the value to an HTMLElement that can be added with appendChild or update the Axis' appendTitleFunction method to accept an html string.

appendTitleFunction: function(textField, val) {
    textField.innerHTML = val;
}
If you use such a strategy, please ensure your content is safe.

appendTitleFunctionFunctionFunction used to add the title attribute to the Axis using appendChild. This attribute can be overridden as needed.
maximumObjectThe maximum value to display on an axis. (TimeAxis and NumericAxis only)
minimumObjectThe minimum value to display on an axis. (TimeAxis and NumericAxis only)
positionStringPosition in relationship to the graph in which to place the axis. (top, right, bottom, left)
roundingMethodStringAlgorithm used for rounding units on a NumericAxis when minimum and maximum are not explicitly set.

Referencing Series and Axis Instances

Sometimes you'll want to update an axis or a series after a chart has been instantiatied. This can be done with the Chart's getAxisByKey and getSeries methods. The getAxisByKey method looks up and returns an Axis instance based on its a key reference.

Using getAxisByKey

var leftAxis = mychart.getAxisByKey("values");
leftAxis.set("styles", {label:{rotation:-45}});

The getSeries method will accept either an index or a key reference and return a series.

Using getSeries with a Key

var mySeries = mychart.getSeries("category");
mySeries.set("visible", false);

Using getSeries with an Index

var mySeries = mychart.getSeries(0);
mySeries.set("visible", false);

Using the legend Attribute

The legend attribute allows you to define a legend for your Chart instance. The legend is an object containing the attributes necessary for defining and styling the legend. Below is a list of the available attributes.

PropertyTypeDescription
chartChartReference to the Chart instance.
directionStringIndicates the direction in relation of the legend's layout. The direction of the legend is determined by its position value.
positionStringIndicates the position and direction of the legend. Possible values are left, top, right and bottom. Values of left and right values have a direction of vertical. Values of top and bottom values have a direction of horizontal.
widthNumberThe width of the legend. Depending on the implementation of the ChartLegend, this value is readOnly. By default, the legend is included in the layout of the Chart that it references. Under this circumstance, width is always readOnly. When the legend is rendered in its own dom element, the readOnly status is determined by the direction of the legend. If the position is left or right or the direction is vertical, width is readOnly. If the position is top or bottom or the direction is horizontal, width can be explicitly set. If width is not explicitly set, the width will be determined by the width of the legend's parent element.
heightNumberThe height of the legend. Depending on the implementation of the ChartLegend, this value is readOnly. By default, the legend is included in the layout of the Chart that it references. Under this circumstance, height is always readOnly. When the legend is rendered in its own dom element, the readOnly status is determined by the direction of the legend. If the position is top or bottom or the direction is horizontal, height is readOnly. If the position is left or right or the direction is vertical, height can be explicitly set. If height is not explicitly set, the height will be determined by the width of the legend's parent element.
xNumberIndicates the x position of legend.
yNumberIndicates the y position of legend.
stylesObject Properties used to display and style the ChartLegend. This attribute is inherited from Renderer. Below are the default values:
gap
Distance, in pixels, between the ChartLegend instance and the chart's content. When ChartLegend is rendered within a Chart instance this value is applied.
hAlign
Defines the horizontal alignment of the items in a ChartLegend rendered in a horizontal direction. This value is applied when the instance's position is set to top or bottom. This attribute can be set to left, center or right. The default value is center.
vAlign
Defines the vertical alignment of the items in a ChartLegend rendered in vertical direction. This value is applied when the instance's position is set to left or right. The attribute can be set to top, middle or bottom. The default value is middle.
item
Set of style properties applied to the items of the ChartLegend.
hSpacing
Horizontal distance, in pixels, between legend items.
vSpacing
Vertical distance, in pixels, between legend items.
label
Properties for the text of an item.
color
Color of the text. The default values is "#808080".
fontSize
Font size for the text. The default value is "85%".
marker
Properties for the item markers.
width
Specifies the width of the markers.
height
Specifies the height of the markers.
styles
Properties for the ChartLegend background.
fill
Properties for the background fill.
color
Color for the fill. The default value is "#faf9f2".
stroke
Properties for the background stroke.
color
Color for the stroke. The default value is "#dad8c9".
weight
Weight of the stroke. The default values is 1.

Known Issues

  • Custom formatting for tooltip's and axis title and labels has been updated for 3.5.0 and higher to prevent potential security vectors. This may cause backward compatibility issues when upgrading from 3.4.x and below under the following circumstances:

    • If you have written a custom labelFunction for your axis that is dependent upon innerHTML for formatting, the current implementation will need to be changed so that it will work with appendChild. Alternatively, there is a newly created appendLabelFunction attribute that can be overridden to use innerHTML. More information can be found under the labelFunction section here.
    • If you are dependent on innerHTML to format the value of an Axis title, you will need to pass in an HTMLElement that can be added using appendChild. Alternatively, there is a newly created appendTitleFunction attribute that can be overridden to use innerHTML. More information can be found under the title section here.
    • If you are using the tooltip attribute's markerLabelFunction or planarLabelFunction to add custom formatting to a chart's tooltip. You will need to update it so that is not dependent on innerHTML. The Customize a Chart's Tooltip example has been updated to demonstrate the correct way to construct a custom tooltip function. Alternatively, there is a newly created setTextFunction property of the tooltip attribute that can be overridden to use innerHTML. More information can be found under the markerLabelFunction and planarLabelFunction sections here.

  • Charts load slowly in android devices. Performance optimizations will need to be added in a future release.

  • Planar interaction with chart types that do not include markers can be confusing. It is not readily apparent where to mouseover to display tooltips. This will be addressed in a future release.

  • Default mouse interactions are not intuitive for touch devices. For example, tooltips show and hide on mouseover and mouseout events. Analysis needs to be done to determine the appropriate default events for touch devices. See the Using the tooltip Attribute section to see how to customize mouse events for the chart.