#
# Primitive example 1
#
import Ngl

npts    = 500
ncurves = 4
ym = Ngl.asciiread("xy2.txt",[npts,ncurves],"float")
x  = Ngl.fspan(-50,50,npts)
y  = ym[:,0]                    # Just grab one set of points.

wks = Ngl.open_wks("x11","poly_ex01")  # Open an X11 window

res  = Ngl.Resources()

res.nglFrame = False              # Don't advance frame.
res.trXMinF  = min(x)             # Put limits on X axis.
res.trXMaxF  = max(x)

plot = Ngl.xy(wks,x,y,res)

Ngl.polymarker(wks,plot,-20,-300)   # Add marker at (-20,-300)

Ngl.frame(wks)

Ngl.end()