;+ ;PROCEDURE: thm_part_subtract ;PURPOSE: Subtracts from a particle distribution down to a minimum. ;(If units are in counts, you can use this to do 1 or N count subtraction) ; ;INPUTS: ; dist_data: ; A particle distribution array from thm_part_dist_array ;OUTPUTS: ; Replaces dat with a data structure with the requested counts subtract ; ;Keywords: ; error: Set to 1 on error, zero otherwise ; subtract_value: The amount to subtract(default: 1) ; minimum_value: The minimum after subtraction.(default 5e-3) Prevents asymptotes in moment calculations, negative values ; ;Example: ; dist_data = thm_part_dist_array(probe='a',type='peif',trange=['2012-02-08/09','2012-02-08/12']) ;load data(loaded in counts, by default) ; thm_part_subtract,dist_data ;subtract one count level ; thm_part_moments,inst='peif',probe='a',dist_array=dist_data ;calculate moments ; ; NOTES: ; Works with thm_part_dist_array.pro, see crib thm_crib_sst_extrapolation.pro, thm_crib_esa_extrapolation.pro for examples on new particle processing routines ; ; $LastChangedBy: pcruce $ ; $LastChangedDate: 2013-01-18 08:57:01 -0800 (Fri, 18 Jan 2013) $ ; $LastChangedRevision: 11462 $ ; $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/spdsoft/trunk/projects/themis/spacecraft/particles/thm_part_subtract.pro $ ;- pro thm_part_subtract,dist_data,error=error,subtract_value=subtract_value,minimum_value=minimum_value compile_opt idl2 error=1 if undefined(dist_data) then begin dprint,dlevel=1,'Error: dist_data undefined' return endif if undefined(subtract_value) then begin subtract_value = 1 endif if undefined(minimum_value) then begin minimum_value = 5e-3 endif ;loops over modes, not times, so this loop is quite efficient, The time-series calculations are fully vectorized for i = 0,n_elements(dist_data)-1 do begin (*dist_data[i]).data= ((*dist_data[i]).data - subtract_value) > minimum_value endfor error=0 end