ENVIAgZones::GetZoneProperty

The GetZoneProperty method retrieves properties (also called attributes) for a specified management zone.

This method requires a separate license for the ENVI Crop Science Module; contact your sales representative for more information.

Example

This example runs AgCreateZones Task to create a classification raster and a zones object named outZones. It retrieves all properties for the zone with a ZONE_ID of 1.

; Start the application

e = ENVI(/HEADLESS)

; Open a DEM file

File = Filepath('FieldDEM.dat', $

  Subdir=['data','crop_science'], $

  Root_Dir=e.Root_Dir)

Raster = e.OpenRaster(File)

; Get the task from the catalog of ENVITasks

Task = ENVITask('AgCreateZones')

; Define inputs

Task.INPUT_RASTER = Raster

Task.MINIMUM_AREA = 2023

Task.NUMBER_OF_APPLICATION_CATEGORIES = 5

; Define outputs

Task.OUTPUT_RASTER_URI = e.GetTemporaryFilename()

; Run the task

Task.Execute

; Get the zones object

outZones = Task.OUTPUT_ZONES

; Get some properties that are specific to

; the zone associated with ZONE_ID=1

outZones.GetZoneProperty, 1, $

  AREA=area, $

  CAT_ID=categoryID, $

  CLASS_NAME=className, $

  CLASS_CLRS=classColors

; Print the values of these properties

Print, 'Area: ',area

Print, 'Category ID: ',categoryID

Print, 'Class Name: ',className

Print, 'Class Colors: ',classColors

Syntax

ENVIAgZones.GetZoneProperty, ZoneID [, Keywords=value]

Arguments

ZoneID

Specify a zone ID from which to extract attributes. If you use AgCreateZones Task to create an ENVIAgZones object, it will create a unique ID for each zone; use one of these for the ZoneID argument.

Keywords

ATTRIBUTES (optional)

Specify a hash containing zone-specific attributes. The hash is not case-sensitive. An attribute is recognized as zone-specific if it is an array or list and the number of elements in the last dimension is equal to the number of zones. Not all zone-specific attributes can be exported to a shapefile. Shapefiles require a one-dimensional array of integers, floating-point values, or strings.

ERROR (optional)

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

PARTS (optional)

Set this keyword to return an array of starting indices of each section of vertices in the specified zone. It is used to identify holes. Zones without holes will have a single-element array, [0].

VERTICES (optional)

Set this keyword to return a [2, n] array of x,y map coordinates for the vertices in the specified zone, where n is the number of points defining the zone.

Version History

Crop Science 1.1

Introduced