ArcGIS Developer Help

IDataSampling Interface

Provides access to members that control the data sampling properties of a renderer.

Product Availability

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

Members

	Name	Description
	MaxSampleSize	Maximum sample size.
	SamplingMethod	Data sampling method.

Classes that implement IDataSampling

Classes	Description
ClassBreaksRenderer	A renderer that can be used to draw graduated color (choropleth) and graduated symbol maps.
LasPointElevationRenderer	LasDataset point renderer component.
TerrainPointAttributeRenderer	Terrain point renderer component.
TerrainPointElevationRenderer	Terrain point renderer component.
TinAspectRenderer	TIN aspect renderer component.
TinElevationRenderer	TIN elevation renderer component.
TinNodeElevationRenderer	TIN node elevation renderer component.
TinSlopeRenderer	TIN slope renderer component.

Remarks

Use this interface to classify data for symbolization based on a subset of features instead of by considering all feature values. More specically, use this interface to specify the maximum number of features to consider when generating class breaks from a classification object.

To perform data sampling using this interface, first instantiate a renderer and set IDataSampling::MaxSampleSize. Next, pass this renderer to a TableHistogram or BasicTableHistogram using ITableHistogram::Sampling. Use IHistogram::GetHistogram to generate a list pair of values and frequencies. Then, classify your data using IClassifyGEN::Classify, passing these lists as parameters. Finally, take the class breaks that were generated by this operation and assign them to your renderer. For example, if working with a ClassBreaksRenderer, set your breaks using IClassBreaksRenderer::Break.

You can also use this interface to check to see if data sampling was used to generate the class breaks for an existing renderer. This works only if the renderer has been assigned by using the standard ArcMap user interface.