ENVISpectralLibrary::GetSpectrum

The GetSpectrum function method returns the details of a specified spectrum.

Example

; Start the application

e = ENVI(/HEADLESS)

; Open a spectral library from the distribution

specLibFile = FILEPATH('veg_1dry.sli', ROOT_DIR=e.ROOT_DIR, $

  SUBDIR=['resource', 'speclib', 'veg_lib'])

specLib = ENVISpectralLibrary(specLibFile)

; print the spectra

Print, specLib.SPECTRA_NAMES

; Get the pinyon pine (sap) spectrum

PinyonPineSap = specLib.GetSpectrum('CDE054: Pinyon Pine (Sap)')

; Plot the spectrum

y = PinyonPineSap.Spectrum

x = PinyonPineSap.Wavelengths

specLibPlot = PLOT(x,y, 'r2', $

  TITLE='CDE054: Pinyon Pine (Sap)', $

  XTITLE='Wavelengths (um)', $
  YTITLE='Data Value')

Syntax

Result = ENVISpectralLibrary.GetSpectrum(SpectrumName [, ERROR=variable])

Return Value

This method returns an IDL dictionary with the following keys:

Name: a string with the name of the spectrum
Spectrum: an array of spectrum values
Wavelengths: an array of the wavelengths of the spectrum
Wavelength_Units: wavelength units
Reflectance_Scale_Factor: the scale factor to use for translating the spectrum to reflectance
Y_Range: the range of spectrum values

Arguments

SpectrumName

Specify a string with the spectrum name to query within an ENVISpectralLibrary. Issuing a PRINT command on the library's SPECTRA_NAMES property is a convenient way to get the spectra names.

Keywords

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

Introduced

API Version

4.2