; docformat = 'rst'
;
; NAME: 
;    getAperture2D
; PURPOSE:
;    Extract a single parameter from multiAperture2D source characterization.
;+
; :Description:
;    Extract a single parameter from multiAperture2D source characterization.
;
; :Categories:
;    Images
;
; :Returns: A single parameter from the input structure.
;
; :Params:
;    param: in, required, type=structure
;      The peak parameters, from multiAperture2D. Fields are:
;      .id:   Parameter simple identifyer
;      .name: Name of the parameter
;      .unit: Unit of the parameter
;      .val:  An array of N values, one per aperture
;      .mean: Average value for N apertures
;      .dev:  Standard deviation for N apertures
;    label: in, required, type=string
;      Parameter ID. Possible values are::
;           radius base peak sigx sigy xc yc tilt EE RMS
;
; :Examples:
;
; :Uses:
;
; :Author:
;    B.Carry (IMCCE)
;
; :History:
;     Change History::
;        Written in April 2015, B. Carry (IMCCE)
;-
function getAperture2D, param, label, index=index


;-----------------------------------------------------------------------------------------------;
;-----------------------------------------------------------------------------------------------;
;---  TAG ---    I -- Initialization And Input Verification              -----------------------;
;-----------------------------------------------------------------------------------------------;
;-----------------------------------------------------------------------------------------------;
  COMPILE_OPT hidden

 ;--I.1-- Check Input Parameters  -------------------------------------------------------
  if not keyword_set(param) or not keyword_set(label) then begin
    message, 'Syntax: plotAperture2d, param, label'
    return, -1
  endif

 ;--I.2-- Peak Model: Gauss or Moffat  --------------------------------------------------
  nbParam = n_elements( param )
  nbMPF = nbParam - 3

 ;--I.3-- Parameter Indices  ------------------------------------------------------------
  indRad = 0
  indPar = 1+indgen(nbMPF)
  indEE  = 1+nbMPF
  indRMS = 1+nbMPF+1


;-----------------------------------------------------------------------------------------------;
;-----------------------------------------------------------------------------------------------;
;---  TAG ---   II -- Determine Parameter Index                          -----------------------;
;-----------------------------------------------------------------------------------------------;
;-----------------------------------------------------------------------------------------------;

 ;--II.1-- Determine Parameter Index  ----------------------------------------------------
  case strlowcase(strtrim(label,2)) of
    'radius': kPar = indRad
    'base'  : kPar = indPar(0)
    'peak'  : kPar = indPar(1)
    'sigx'  : kPar = indPar(2)
    'sigy'  : kPar = indPar(3)
    'xc'    : kPar = indPar(4)
    'yc'    : kPar = indPar(5)
    'tilt'  : kPar = indPar(6)
    'index' : kPar = indPar(7)
    'ee'    : kPar = indEE
    'rms'   : kPar = indRMS
    else:
  endcase


 ;--II.2-- Return Single Parameter Structure  --------------------------------------------
  if keyword_set(index) then return, kPar $
                        else return, param(kPar)

end