# NOT RUN { require(graphics) ## using poly: this did not work in R < 1.5.0 fm <- lm(weight ~ poly(height, 2), data = women) plot(women, xlab = "Height (in)", ylab = "Weight (lb)") ht <- seq(57, 73, len = 200) nD <- data.frame(height = ht) pfm <- predict(fm, nD) lines(ht, pfm) pf2 <- predict(update(fm, ~ stats::poly(height, 2)), nD) stopifnot(all.equal(pfm, pf2)) ## was off (rel.diff. 0.0766) in R <= 3.5.0 ## see also example(cars) ## see bs and ns for spline examples. # }
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