Dear John, It occurs to me that the title above the graph, "Residuals vs. Leverage," is entirely redundant since the x-axis is labelled "Leverage" and the y-axis "Studentized residuals." Why not use the title above the graph for "Cook's distance countours"?
Regards, John > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of John Maindonald > Sent: February-17-09 5:54 PM > To: [email protected] > Cc: Martin Maechler > Subject: [Rd] plot.lm: "Cook's distance" label can overplot point labels > > The following code demonstrates an annoyance with plot.lm(): > > library(DAAGxtras) > x11(width=3.75, height=4) > nihills.lm <- lm(log(time) ~ log(dist) + log(climb), data = nihills) > plot(nihills.lm, which=5) > > OR try the following > xy <- data.frame(x=c(3,1:5), y=c(-2, 1:5)) > plot(lm(y ~ x, data=xy), which=5) > > The "Cook's distance" text overplots the label for the point with the > smallest residual. This is an issue when the size of the plot is much > less than the default, and the pointsize is not reduced proportionately. > > > I suggest the following: > xx <- hii > xx[xx >= 1] <- NA > ## Insert new code > fracht <- (1.25*par()$cin[2])/par()$pin[2] > ylim[1] <- ylim[1] - diff(ylim)*max(0, fracht-0.04) > ## End insert new code > plot(xx, rsp, xlim = c(0, max(xx, na.rm = TRUE)), > ylim = ylim, main = main, xlab = "Leverage", > ylab = ylab5, type = "n", ...) > > Then, about 15 lines further down, replace > legend("bottomleft", legend = "Cook's distance", > lty = 2, col = 2, bty = "n") > > by > legend("bottomleft", legend = "Cook's distance", > lty = 2, col = 2, bty = "n", y.intersp=0.5) > > If this second change is not made, then one wants fracht <- (1.5*par() > $cin[2])/par()$pin[2] > I prefer the "Cook's distance" text to be a bit closer to the x-axis, > as it separates it more clearly from any point labels. > > John Maindonald email: [email protected] > phone : +61 2 (6125)3473 fax : +61 2(6125)5549 > Centre for Mathematics & Its Applications, Room 1194, > John Dedman Mathematical Sciences Building (Building 27) > Australian National University, Canberra ACT 0200. > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
