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Query feature count and extent

Zoom to features matching a query and count the features in the current visible extent.

How to use the sample

Use the button to zoom to the extent of a state or use the button to count the features in the current extent.

How it works

Querying by state abbreviation:

  1. A QueryParameters object is created with a WhereClause.
  2. FeatureTable.QueryExtentAsync is called with the QueryParameters object to obtain the extent that contains all matching features.
  3. The extent is converted to a Viewpoint, which is passed to MapView.SetViewpointAsync.

Counting features in the current extent:

  1. The current visible extent is obtained from a call to MapView.GetCurrentViewpoint(ViewpointType).
  2. A QueryParameters object is created with the visible extent and a defined SpatialRelationship (in this case 'intersects').
  3. The count of matching features is obtained from a call to FeatureTable.QueryFeatureCountAsync.

Relevant API

  • QueryParameters
  • QueryParameters.WhereClause
  • QueryParameters.Geometry
  • QueryParameters.SpatialRelationship
  • FeatureTable.QueryExtentAsync
  • FeatureTable.QueryFeatureCountAsync
  • MapView.GetCurrentViewpoint(ViewpointType)

About the data

See the layer on ArcGIS Online

This map shows hospital spending per-patient for common incidents. Hospitals in blue/turquoise spend less than the national average. Red/salmon indicates higher spending relative to other hospitals, while gray is average.

Tags

Feature layer, Feature table, Query, Medicare