;------------------------------------------------------------------------------
;Make some "data" arrays, with some gaps in the x's.  Note that
; the first and last points are isolated, just to test the algorithm.
;
x=[0,2,3,4,5,6,7,8,9,12,13,14,15,17]
y= RANDOMN(seed,14)

;Create the plotting area.  Don't draw symbols now, as
; they may get overwritten by a black (invisible) line.
;
plot,x,y,/NODATA

;For X values separated by one stepsize (1 in this case),
; the following logical statement will be true (1).  Larger
; steps will be false.  Note that the first element of color
; will be junk, but that's okay, as the PLOTS command doesn't use it.
;
stepsize= 1
color= (x - shift(x,1)) EQ stepsize

;Use the COLOR keyword to PLOTS.  This will work for background=0,
; drawing color=255.  Modify as necessary.
;
plots,x,y,COLOR=color*255
plots,x,y,PSYM=4

END
;------------------------------------------------------------------------------