;+
; NAME:
;  matchfirst
; PURPOSE: (one line)
;  return the index of the first match of an element to an array
; DESCRIPTION:
;  
; CATEGORY:
;  Util
; CALLING SEQUENCE:
;  match = firstmatch(elem, array)
; INPUTS:
;  element - the element to be match
;  list - the list into which an index should be returned
; OPTIONAL INPUT PARAMETERS:
;  none
; KEYWORD INPUT PARAMETERS:
;  none
; KEYWORD OUTPUT PARAMETERS:
;  none
; OUTPUTS:
;  long, same dimensions as elem.
;  -1 if elem[i] is not in array
;  array(match[i]) = elem[i], if match[i] ne -1
; COMMON BLOCKS:
;  None
; SIDE EFFECTS:
; RESTRICTIONS:
;  None
; PROCEDURE:
; MODIFICATION HISTORY:
;  2009 Sept 4 Leslie Young SwRI
;-

function matchfirst, elem, list
    if isarray(elem) then begin
       n = n_elements(elem)
       if size(elem, /tname) eq 'STRING' then begin
          res = long(elem eq '') ; to get the right dimensions.  
       endif else begin
          res = long(elem)      ; to get the right dimensions.  
       endelse
                                ; Fix first, in case res is a string.
       for i = 0L, n-1 do res[i] = (where(elem[i] eq list))[0]
       return, res
    endif else begin
       return, (where(elem eq list))[0]
    endelse
end