[R] possible issue with scatterplot function in car package

Fox, John j|ox @end|ng |rom mcm@@ter@c@
Sun May 3 05:47:21 CEST 2020


Dear Yousri,

Yes, this is clearly a bug, and almost surely a long-standing one. We'll fix it in the next release of the car package.

BTW, stringsAsFactors defaults to FALSE in R 4.0.0 (and you don't use the ch variable in the example). Also, although it has no bearing on the bug, I'd generally prefer

	scatterplot(y ~ x, data=aa, smooth=FALSE, grid=FALSE, 
            	frame=FALSE, regLine=FALSE, xlim=c(0, 8))

Thank you for the bug report,
 John

  -----------------------------
  John Fox, Professor Emeritus
  McMaster University
  Hamilton, Ontario, Canada
  Web: http::/socserv.mcmaster.ca/jfox

> On May 2, 2020, at 7:30 PM, Yousri Fanous <yousri.fanous using gmail.com> wrote:
> 
> library (car)
> 
> aa <- data.frame(x=c(2,  5, 6, 7, 8),
> +  y=c(5,  10, 9, 12, 11),
> + ch=c("N",  "Q", "R", "S", "T"),
> + stringsAsFactors=FALSE)
> 
> scatterplot(aa$x,aa$y,smooth = FALSE, grid = FALSE, frame = FALSE,regLine=F)
> 
> Both x and y boxplots are correct
> and in particular the median of the x box is at 6 which is confirmed
> 
>> median(aa$x)
> [1] 6
> 
> Now I do only one addition to the scatterplot: I add xlim
>> scatterplot(aa$x,aa$y,smooth = FALSE, grid = FALSE, frame =
> FALSE,regLine=F,xlim=c(0,8))
> 
> This causes the boxplot on x-axis to be in error:
> 1) the lower whisker starts now from zero
> 2) the median is between 4 and 6 and no longer at 6 as before
> 
>> sessionInfo()
> R version 3.6.3 (2020-02-29)
> [1] car_3.0-7
> 
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> 
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