com.esri.arcgis.system
Class NaturalBreaks

java.lang.Object
  com.esri.arcgis.system.NaturalBreaks

All Implemented Interfaces:

com.esri.arcgis.interop.RemoteObjRef, IClassify, IClassifyGEN, Serializable

public class NaturalBreaks
extends Object
implements com.esri.arcgis.interop.RemoteObjRef, IClassifyGEN, IClassify

Defines a natural breaks classification method.

Description

The NaturalBreaks coclass uses a statistical formula to determine natural clusters of attribute values. The formula is known as Jenk’s method. This attempts to minimize the variance within a class and to maximize the variance between classes. The natural-breaks classification is well suited to uneven distributions of attributes. Distinct natural groupings of attributes can be isolated and highlighted.

This classification only uses the IClassify interface, so there is nothing to set up other than calling IClassify::SetHistogramData.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Supported Platforms

Windows, Solaris, Linux

See Also:

Serialized Form

Constructor Summary

NaturalBreaks()
Constructs a NaturalBreaks using ArcGIS Engine.

NaturalBreaks(Object obj)
Deprecated. As of ArcGIS 9.2, replaced by normal Java casts.
NaturalBreaks theNaturalBreaks = (NaturalBreaks) obj;

Method Summary

void	classify(int[] numClasses) Classifies data into the specified number of classes.
void	classify(Object doubleArrayValues, Object longArrayFrequencies, int[] numClasses) Deprecated. This method uses C style arrays which are not supported in the ArcGIS API for Java. It is replaced by SystemHelper.classify(com.esri.arcgis.system.IClassifyGEN, double[], int[], int[]).
boolean	equals(Object o) Compare this object with another
Object	getClassBreaks() The array of class breaks (double).
IUID	getClassID() The CLSID for the classification object.
static String	getClsid() getClsid.
String	getMethodName() The name of the classification method (based on choice of classification object).
int	hashCode() the hashcode for this object
void	setHistogramData(Object doubleArrayValues, Object longArrayFrequencies) Adds data in form of a histogram (array of values (doubles) and a paired array of frequencies (longs)) to the classification.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.esri.arcgis.interop.RemoteObjRef

getJintegraDispatch, release

Constructor Detail

NaturalBreaks

public NaturalBreaks()
              throws IOException,
                     UnknownHostException

Constructs a NaturalBreaks using ArcGIS Engine.

Throws:

IOException - if there are interop problems

UnknownHostException - if there are interop problems

NaturalBreaks

public NaturalBreaks(Object obj)
              throws IOException

Deprecated. As of ArcGIS 9.2, replaced by normal Java casts.
NaturalBreaks theNaturalBreaks = (NaturalBreaks) obj;

Construct a NaturalBreaks using a reference to such an object returned from ArcGIS Engine or Server. This is semantically equivalent to casting obj to NaturalBreaks.

Parameters:

obj - an object returned from ArcGIS Engine or Server

Throws:

IOException - if there are interop problems

Method Detail

getClsid

public static String getClsid()

getClsid.

equals

public boolean equals(Object o)

Compare this object with another

Overrides:

equals in class Object

hashCode

public int hashCode()

the hashcode for this object

Overrides:

hashCode in class Object

classify

public void classify(Object doubleArrayValues,
                     Object longArrayFrequencies,
                     int[] numClasses)
              throws IOException,
                     AutomationException

Deprecated. This method uses C style arrays which are not supported in the ArcGIS API for Java. It is replaced by SystemHelper.classify(com.esri.arcgis.system.IClassifyGEN, double[], int[], int[]).

Classifies histogram data (array of values (doubles) and a paired array of frequencies (longs)) into the specified number of classes.

Description

Classify generates the ClassBreaks based upon the numeric data passed and the number of classes specified.

Pass two safe arrays to the Classify method that must have the same number of elements and an index of zero for their first element. The first array (doubeArrayValues) is the numeric data values, defined as an array of double. This array must be sorted in increasing value order. The second array (longArrayFrequencies) represents the frequency of occurrence of the values, that is, an integer count of the number of times a value occurs.

For example, if the two arrays were called DataValues and DataFrequency, the lowest value would be stored in DataValue(0), and the number of times this value occurred would be stored in DataFrequency(0).

You could populate these arrays in code yourself, but if the data is available through the attribute field of a table, you can utilize the TableHistogram object to gather the data values and frequencies for you.

You must supply the number of desired classes as a variable defined as a Long. Some classification algorithms will return a different number of class breaks to what you specified. The number of classes will be written back to the variable you supplied, so it is always best to recheck the number of class breaks after calling Classify.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Specified by:

classify in interface IClassifyGEN

Parameters:

doubleArrayValues - A Variant (in)

longArrayFrequencies - A Variant (in)

numClasses - The numClasses (in/out: use single element array)

Throws:

IOException - If there are interop problems.

AutomationException - If the ArcObject component throws an exception.

getClassBreaks

public Object getClassBreaks()
                      throws IOException,
                             AutomationException

The array of class breaks (double). ClassBreaks(0) is the minimum value in the dataset, and subsequent breaks represent the upper limit of each class.

Description

ClassBreaks returns an array of class breaks. The number of breaks may be different than what was specified in the Classify method, so it is essential that you check this before setting the BreakCount on IClassBreaksRenderer . The reason this may be different has to do with how a particular classification method handles skewness in the data being classified.

The first ClassBreak returned is the minimum value of the data being classified. The rest of the breaks are the upper bounds for each class. The last break represents the upper bound of the highest class.

To properly assign ClassBreaks to an IClassBreaksRenderer:

1. Set IClassBreaksRenderer.MinimumBreak = IClassify.ClassBreaks(0)

2. Set IClassBreaksRenderer.Breaks(0) = IClassify.ClassBreaks(1)

3. Set IClassBreaksRenderer.Breaks(1) = IClassify.ClassBreaks(2)

etc.

Remarks

Note that the Breaks property array on the ClassBreaksRenderer has one less entry than the array returned from Classify. The first break value in the array returned from Classify is put into the ClassBreakRenderers’ MinimumBreak property. Next, copy the break values into the ClassBreaksRenderer object. You can set up the symbol property of the classes at the same time.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Specified by:

getClassBreaks in interface IClassify

Specified by:

getClassBreaks in interface IClassifyGEN

Returns:

A Variant

Throws:

IOException - If there are interop problems.

AutomationException - If the ArcObject component throws an exception.

getMethodName

public String getMethodName()
                     throws IOException,
                            AutomationException

The name of the classification method (based on choice of classification object).

Description

MethodName returns the classification method name (as it appears in the classification dialog). Use to determine the CoClass currently implementing IClassifyGEN.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Specified by:

getMethodName in interface IClassify

Specified by:

getMethodName in interface IClassifyGEN

Returns:

The txt

Throws:

IOException - If there are interop problems.

AutomationException - If the ArcObject component throws an exception.

See Also:

StandardDeviation, EqualInterval, NaturalBreaks, ClassBreaksRenderer, DefinedInterval, Quantile

getClassID

public IUID getClassID()
                throws IOException,
                       AutomationException

The CLSID for the classification object.

Description

Returns the GUID of the classification object.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Specified by:

getClassID in interface IClassify

Specified by:

getClassID in interface IClassifyGEN

Returns:

A reference to a com.esri.arcgis.system.IUID

Throws:

IOException - If there are interop problems.

AutomationException - If the ArcObject component throws an exception.

setHistogramData

public void setHistogramData(Object doubleArrayValues,
                             Object longArrayFrequencies)
                      throws IOException,
                             AutomationException

Adds data in form of a histogram (array of values (doubles) and a paired array of frequencies (longs)) to the classification.

Description

To pass numeric data into the Classify object, the SetHistogramData method is used. This takes two safe arrays that must have the same number of elements and an index of zero for their first element. The first array is the numeric data values, defined as an array of double. This array must be sorted in increasing value order. The second array represents the frequency of occurrence of the values, that is, an integer count of the number of times a value occurs.

For example, if the two arrays were called DataValues and DataFrequency, the lowest value would be stored in DataValue(0), and the number of times this value occurred would be stored in DataFrequency(0).

You could populate these arrays in code yourself, but if the data is available through the attribute field of a table, you can utilize the TableHistogram object to gather the data values and frequencies for you.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Supported Platforms

Windows, Solaris, Linux

Specified by:

setHistogramData in interface IClassify

Parameters:

doubleArrayValues - A Variant (in)

longArrayFrequencies - A Variant (in)

Throws:

IOException - If there are interop problems.

AutomationException - If the ArcObject component throws an exception.

classify

public void classify(int[] numClasses)
              throws IOException,
                     AutomationException

Classifies data into the specified number of classes.

Description

Classify generates the ClassBreaks given the number of classes specified. Use Classify only after you have added data to the classification using SetHistogramData.

Remarks

Having obtained the data values and frequencies using the SetHistogramData method, the next step is to compute some class breaks. Do this by calling the Classify method and specifying the number of classes you would like. You must supply the number of desired classes as a variable defined as a Long. Some classification algorithms will return a different number of class breaks to what you specified. The number of classes will be written back to the variable you supplied, so it is always best to recheck the number of class breaks after calling Classify.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Supported Platforms

Windows, Solaris, Linux

Specified by:

classify in interface IClassify

Parameters:

numClasses - The numClasses (in/out: use single element array)

Throws:

IOException - If there are interop problems.

AutomationException - If the ArcObject component throws an exception.