From: John Fox <jfox_at_mcmaster.ca>

Date: Tue, 17 Feb 2009 20:27:21 -0500

R-devel_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-devel Received on Wed 18 Feb 2009 - 00:30:15 GMT

Date: Tue, 17 Feb 2009 20:27:21 -0500

> -----Original Message-----

*> From: r-devel-bounces_at_r-project.org [mailto:r-devel-bounces_at_r-project.org]
*

On

*> Behalf Of John Maindonald
*

> Sent: February-17-09 5:54 PM

*> To: r-devel_at_r-project.org
**> 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: john.maindonald_at_anu.edu.au
**> 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.
**>
**> ______________________________________________
**> R-devel_at_r-project.org mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-devel
*

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