pro subsample, A, B, suba, subb, delta,COUNT = count,KS = ks
;+
; NAME:
;       subsample
; PURPOSE:
;       Routine to get the sub sample of A and B
;       these two subsaples are supposed to follow the same distribution
;
; CALLING SEQUENCE:
;       subsample, A, B, suba, subb, count = count, KS = ks
;
; INPUTS:
;       A,B - two samples, its better to set A have less elements than B
;       delta - the allowed difference between a and b
;
; OUTPUTS:
;       suba - subscripts of elements in sample A with a match
;               in sample B
;       subb - subscripts of elements in sample B with a match
;               in sample a.
;  OPTIONAL KEYWORD OUTPUT:
;       COUNT - number of the elements of the sub sample
;		KS - KS test results between SA and SB where SA=a[suba] and SB=b[subb]
;
; HISTORY:
;		Shiyin Shen Jan. 2015
;
;-
;-------------------------------------------------------------------------
 
NA=N_elements(A)
NB=N_elements(B)
Bflag=intarr(NB)
Is=0
for i=0L,NA-1 do begin
	diff=abs(B-A[i])
	sel=where(diff lt delta and Bflag eq 0,Nsel)
	if Nsel gt 0 then begin
		mdiff=min(diff[sel],mloc)
		if IS eq 0 then begin
			suba=i
			subb=sel[mloc]
		endif else begin
			suba=[suba,i]
			subb=[subb,sel[mloc]]
		endelse
		Bflag[sel[mloc]]=1
		Is=Is+1
	endif
endfor

count=Is
if(Is gt 0) then begin
	Kstwo,A[suba],B[subb],D,prob
	ks=prob
	if prob lt 0.5 then begin
		print,'Caution KS test of two subsample with prob',prob
	endif
endif


end