;+ ; NAME: ; round2array ; ; ; PURPOSE: ; round a value to its nearest value in an array ; ; ; INPUTS: ; array: SORTED!! array to round the number into (must be 1-d) ; number: the number(s) to round to the array ; ; KEYWORD PARAMETERS: ; FORCE: force the program to return an answer even if the input is ; not sorted ; ; ; OUTPUTS: ; the index of the closest array element ; ; RESTRICTIONS: ; not fully tested for nan values... ; ; ; ; EXAMPLE: ; IDL> print, round2array(findgen(10), [3.4, 3.0, 6.7, 6.3]) ; 3 3 7 6 ; ; MODIFICATION HISTORY: ; ; Mon Sep 8 15:39:23 2008, Brian Larsen ; ; had a problem at the end point, fixed, probably lost ; some speed however ; ; Tue Aug 26 18:42:58 2008, Brian Larsen ; ; another x10 speed improvement suggested by Paolo ; Grigis ; http://groups.google.com/group/comp.lang.idl-pvwave/browse_frm/thread/5848f460a7aab59b/1aae381879eb7ef9#1aae381879eb7ef9 ; ; Mon Jan 7 10:46:02 2008, Brian Larsen ; ; totally rewritten using value_locate greatly ; simplified and sped up (factor of 11) ; Changed order of inputs to ; match that of value_locate (sorry) ; ; Tue Oct 16 14:51:20 2007, Brian Larsen ; ; written and tested ; ;- FUNCTION round2array, array, number, FORCE = force n_a = n_elements(array) IF n_a EQ 0 THEN $ message, /ioerror, 'must input an array' IF is_sorted(array) EQ 0 AND ~keyword_set(force) THEN $ message, 'Input array must be sorted' vl = value_locate(array, number) ind_max = where(vl EQ n_elements(array)-1, n_ind_max, comp = comp) IF n_ind_max LT n_elements(number) THEN $ vl[comp] += ( (number-array[vl[comp]]) GT (array[vl[comp]+1]-number)) IF n_ind_max NE 0 THEN $ vl[ind_max] = n_elements(array)-1 IF total(vl LT 0) NE 0 THEN BEGIN ind = where(vl LT 0, n_ind) vl[ind] = 0 ENDIF IF total(vl GT n_elements(array)-1) THEN BEGIN ind = where(vl GT n_elements(array)-1, n_ind) vl[ind] = n_elements(array-1) ENDIF return, vl END