mx.charts.LogAxis - Adobe® Flex® 4 Language Reference (Flex 4)

Package	mx.charts
Class	public class LogAxis
Inheritance	LogAxis NumericAxis AxisBase EventDispatcher Object

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

The LogAxis class maps numeric values logarithmically between a minimum and maximum value along a chart axis. By default, it determines minimum, maximum, and interval values from the charting data to fit all of the chart elements on the screen. You can also explicitly set specific values for these properties. A LogAxis object cannot correctly render negative values, as Log10() of a negative number is undefined.

MXML Syntax expanded

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The <mx:LogAxis> tag inherits all the properties of its parent classes and adds the following properties:

  <mx:LogAxis
    Properties
    interval="10"
    maximum="null"
    maximumLabelPrecision="null"
    minimum="null"
  />

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Public Properties

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	Property		Defined By
		autoAdjust : Boolean Specifies whether Flex rounds values.	NumericAxis
		baseAtZero : Boolean Specifies whether Flex tries to keep the minimum and maximum values rooted at zero.	NumericAxis
		baseline : Number [read-only] The computed minimum value for the axis as long as this value is greater than 0.	NumericAxis
		chartDataProvider : Object [write-only] The data provider assigned to the enclosing chart.	AxisBase
		computedMaximum : Number The computed maximum value represented by this axis.	NumericAxis
		computedMinimum : Number The computed minimum value represented by this axis.	NumericAxis
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		direction : String Determines the direction in which the axis is rendered.	NumericAxis
		displayName : String The name of the axis.	AxisBase
		interval : Number Specifies the multiplier label values along the axis.	LogAxis
		labelFunction : Function Called to format axis values for display as labels.	NumericAxis
		maximum : Number Specifies the maximum value for an axis label.	LogAxis
		maximumLabelPrecision : Number Specifies the maximum number of decimal places for representing fractional values on the labels generated by this axis.	LogAxis
		minimum : Number Specifies the minimum value for an axis label.	LogAxis
		minorTicks : Array [read-only] An Array of minor tick marks generated to represent this axis.	NumericAxis
		padding : Number Specifies padding that Flex adds to the calculated minimum and maximum values for the axis when rendering the values on the screen.	NumericAxis
		parseFunction : Function Specify a parseFunction to customize how the values rendered by your chart are converted into numeric values.	NumericAxis
		prototype : Object [static] A reference to the prototype object of a class or function object.	Object
		title : String The text for the title displayed along the axis.	AxisBase
		unitSize : Number [read-only] The size of one unit of data as represented by this axis.	AxisBase

Protected Properties

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	Property		Defined By
		assignedMaximum : Number The explicitly assigned maximum value.	NumericAxis
		assignedMinimum : Number The explicitly assigned minimum value.	NumericAxis
		computedInterval : Number The computed interval represented by this axis.	NumericAxis
		dataDescriptions : Array [read-only] An Array of DataDescription structures describing the data being represented by the chart.	NumericAxis
		labelCache : Array The most recent set of AxisLabel objects generated to represent this axis.	NumericAxis
		labelMaximum : Number The maximum value where a label should be placed.	NumericAxis
		labelMinimum : Number The minimum value where a label should be placed.	NumericAxis
		minorTickCache : Array The most recent set of minor tick marks generated to represent this axis.	NumericAxis
		requiredDescribedFields : uint [read-only] The fields of the DescribeData structure that this axis is interested in.	NumericAxis
		ticks : Array [read-only] An Array of tick marks for this axis.	NumericAxis

Public Methods

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	Method		Defined By
		LogAxis() Constructor.	LogAxis
		addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.	EventDispatcher
		dataChanged():void Triggers events that inform the range object when the chart data has changed.	AxisBase
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	EventDispatcher
		filterCache(cache:Array, field:String, filteredField:String):void Filters a set of values of arbitrary type to a set of numbers that can be mapped.	NumericAxis
		formatForScreen(value:Object):String Formats values for display in DataTips.	NumericAxis
		getLabelEstimate():AxisLabelSet Determines the range to estimate what the axis labels should be.	NumericAxis
		getLabels(minimumAxisLength:Number):AxisLabelSet Gets the labels text that is rendered.	NumericAxis
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	EventDispatcher
		hasOwnProperty(name:String):Boolean Indicates whether an object has a specified property defined.	Object
		invertTransform(value:Number):Object Maps a position along the axis back to a numeric data value.	NumericAxis
		isPrototypeOf(theClass:Object):Boolean Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.	Object
		mapCache(cache:Array, field:String, convertedField:String, indexValues:Boolean = false):void Converts a set of values of arbitrary type to a set of numbers that can be transformed into screen coordinates.	NumericAxis
		preferDropLabels():Boolean Determines how the axis handles overlapping labels.	NumericAxis
		propertyIsEnumerable(name:String):Boolean Indicates whether the specified property exists and is enumerable.	Object
		reduceLabels(intervalStart:AxisLabel, intervalEnd:AxisLabel):AxisLabelSet Invoked when an AxisRenderer is unable to cleanly render the labels without overlap, and would like the Axis object to reduce the set of labels.	NumericAxis
		registerDataTransform(transform:mx.charts.chartClasses:DataTransform, dimensionName:String):void Each DataTransform that makes use of an axis registers itself with that axis.	AxisBase
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	EventDispatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	Object
		toLocaleString():String Returns the string representation of this object, formatted according to locale-specific conventions.	Object
		toString():String Returns the string representation of the specified object.	Object
		transformCache(cache:Array, field:String, convertedField:String):void Maps a set of values from data space to screen space.	NumericAxis
		unregisterDataTransform(transform:mx.charts.chartClasses:DataTransform):void Each DataTransform that makes use of an axis registers itself with that axis.	AxisBase
		update():void Updates the chart.	NumericAxis
		valueOf():Object Returns the primitive value of the specified object.	Object
		willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.	EventDispatcher

Protected Methods

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	Method		Defined By
		adjustMinMax(minValue:Number, maxValue:Number):void Adjusts the generated or assigned range of the axis's labels.	NumericAxis
		buildLabelCache():Boolean Populates the labelCache property with labels representing the current values of the axis.	NumericAxis
		buildMinorTickCache():Array Builds an Array of positions for the minor tick marks Array that is generated by this axis.	NumericAxis
		describeData(requiredFields:uint):Array Called by the governing DataTransform to obtain a description of the data represented by this IChartElement.	AxisBase
		guardMinMax(min:Number, max:Number):Array Protects the range against invalid values for this axis type.	NumericAxis
		invalidateCache():void Invalidates the cached labels and tick marks that represent this axis's values.	NumericAxis

Events

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	Event		Summary	Defined By
		activate	[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.	EventDispatcher
		deactivate	[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.	EventDispatcher

Property Detail

interval

property

interval:Number

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Specifies the multiplier label values along the axis. A value of 10 generates labels at 1, 10, 100, 1000, etc., while a value of 100 generates labels at 1, 100, 10000, etc. Flex calculates the interval if this property is set to NaN. Intervals must be even powers of 10, and must be greater than or equal to 10. The LogAxis rounds the interval down to an even power of 10, if necessary.

The default value is 10.

Implementation
public function get interval():Number
public function set interval(value:Number):void

maximum

property

maximum:Number

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Specifies the maximum value for an axis label. If NaN, Flex determines the maximum value from the data in the chart. The maximum value must be an even power of 10. The LogAxis rounds an explicit maximum value up to an even power of 10, if necessary.

The default value is NaN.

Implementation
public function get maximum():Number
public function set maximum(value:Number):void

maximumLabelPrecision

property

maximumLabelPrecision:Number

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Specifies the maximum number of decimal places for representing fractional values on the labels generated by this axis. By default, the Axis autogenerates this value from the labels themselves. A value of 0 round to the nearest integer value, while a value of 2 rounds to the nearest 1/100th of a value.

Implementation
public function get maximumLabelPrecision():Number
public function set maximumLabelPrecision(value:Number):void

minimum

property

minimum:Number

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Specifies the minimum value for an axis label. If NaN, Flex determines the minimum value from the data in the chart. The minimum value must be an even power of 10. The LogAxis will round an explicit minimum value downward to an even power of 10 if necessary.

The default value is NaN.

Implementation
public function get minimum():Number
public function set minimum(value:Number):void

Constructor Detail

LogAxis

()

Constructor

public function LogAxis()

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Constructor.

Examples How to use this example

LogAxisExample.mxml

<?xml version="1.0"?>
<!-- Simple example to demonstrate the LogAxis class. -->
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
    xmlns:s="library://ns.adobe.com/flex/spark" 
    xmlns:mx="library://ns.adobe.com/flex/mx">

    <fx:Script>
        <![CDATA[

        import mx.collections.ArrayCollection;

        [Bindable]
        private var expensesAC:ArrayCollection = new ArrayCollection( [
            { Month: "Jan", Profit: 20000, Expenses: 1500, Amount: 450 },
            { Month: "Feb", Profit: 1000, Expenses: 15000, Amount: 600 },
            { Month: "Mar", Profit: 15000, Expenses: 5000, Amount: 300 },
            { Month: "Apr", Profit: 1800, Expenses: 1200, Amount: 900 },
            { Month: "May", Profit: 2400, Expenses: 575, Amount: 500 } ]);
        ]]>
    </fx:Script>

    <mx:Panel title="LogAxis Example" height="100%" width="100%">

        <mx:LineChart id="linechart" height="100%" width="100%"
            paddingLeft="5" paddingRight="5" 
            showDataTips="true" dataProvider="{expensesAC}">
                
            <mx:horizontalAxis>
                <mx:CategoryAxis categoryField="Month"/>
            </mx:horizontalAxis>
                
            <mx:verticalAxis>
                <mx:LogAxis interval="10"/>
            </mx:verticalAxis>
                
            <mx:series>
                <mx:LineSeries yField="Profit" form="curve" displayName="Profit"/>
                <mx:LineSeries yField="Expenses" form="curve" displayName="Expenses"/>
                <mx:LineSeries yField="Amount" form="curve" displayName="Amount"/>
            </mx:series>
        </mx:LineChart>

        <mx:Legend dataProvider="{linechart}"/>

    </mx:Panel>
</s:Application>