# enlarge regular grid
# create x and y defining square border
x = seq(min(lon), max(lon), length = 60)
y = seq(min(lat), max(lat), length = 80)
border = border.grid(x, y)
e = enlarge(border)
plot(e)
# create x and y defininging an irregular grid
border2 = border.grid(lon, lat)
e2 = enlarge(border2)
plot(e2)
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