w <- vect("POLYGON ((0 -5, 10 0, 10 -10, 0 -5))")
is.valid(w)
w <- vect("POLYGON ((0 -5, 10 0, 10 -10, 4 -2, 0 -5))")
is.valid(w)
is.valid(w, TRUE)
plot(w)
points(cbind(4.54, -2.72), cex=2, col="red")
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