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ENVIRasterMetadata::HasTag

ENVIRasterMetadata::HasTag

The HasTag function method checks if a specified metadata field exists.

Example


PRO SetDataIgnoreValue
COMPILE_OPT IDL2
 
  ; Launch the application
  e = ENVI()
   
  ; Create an ENVIRaster
  file = FILEPATH('qb_boulder_msi', ROOT_DIR=e.ROOT_DIR, $
    SUBDIRECTORY = ['data'])
  raster = e.OpenRaster(file)
   
  ; Check if the metadata contains a data ignore
  ; value field. If so, update it. If not, add it.
  metadata = raster.METADATA
  IF (metadata.HasTag ('data ignore value')) THEN BEGIN
    metadata.UpdateItem, 'data ignore value', 0.0
  ENDIF ELSE BEGIN
    metadata.AddItem, 'data ignore value', 0.0
  ENDELSE
   
  ; Create a scratch output file
  newFile = e.GetTemporaryFilename()
   
  ; Export to a new file and update the header
  raster.Export, newFile, 'envi'
   
  ; Open the ENVI file
  raster1 = e.OpenRaster(newFile)
  view = e.GetView()
  layer = view.CreateLayer(raster1)
END

Syntax


Result = ENVIRasterMetadata.HasTag(Tag, [, ERROR=variable])

Arguments


Tag

The tag name of the metadata item you wish to add. Metadata tags are defined by the file format from which the ENVIRaster was opened. Consult your data provider or file format specification for more information on metadata fields for specific sensors and/or data formats (GeoTIFF, NITF, and others).

Keywords


Keywords are applied only during the initial creation of the object.

ERROR

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.

Version History


ENVI 5.3, Service Pack 1

Introduced

API Version


3.3

See Also


ENVIRasterMetadata, ENVIRasterMetadata.AddItem, ENVIRasterMetadata::RemoveItem, ENVIRasterMetadata::UpdateItem, ENVIRaster's METADATA property



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