; This batch file creates a plot used in Chapter 10, "Plotting",
; of _Using IDL_.

; Define variables.

@plot01

; Draw axes with no data, setting the data range.

PLOT, YEAR, CHINOOK, YRANGE = [MIN(SOCKEYE), MAX(CHINOOK)], /NODATA, $
    TITLE='Chinook and Sockeye Populations', XTITLE='Year', $
    YTITLE='Fish (thousands)'

; Make a vector of x values for the polygon by duplicating the first
; and last points.

PXVAL = [YEAR(0), YEAR, YEAR(N1)]

; Get y value along bottom x-axis.

MINVAL = !Y.CRANGE(0)	

; Make a polygon by extending the edges of the math score down
; to the x-axis.

POLYFILL, PXVAL, [MINVAL, CHINOOK, MINVAL], $
    COL = 0.75 * !D.N_COLORS	

; Do the same with the verbal score.

POLYFILL, PXVAL, [MINVAL, SOCKEYE, MINVAL], $
    COL = 0.50 * !D.N_COLORS

; Label the polygons.

XYOUTS, 1968, 430, 'SOCKEYE', SIZE=2
XYOUTS, 1968, 490, 'CHINOOK', SIZE=2