[R] Changing x-axis on boxplot

[Theresa Csar]

Hi,

to hide the axis generated by bxp you have to set axes=FALSE and 
frame.plot=FALSE and then you can plot the x-axis by using the axis() 
function

example:

boxplot(len ~ dose, data = ToothGrowth,
    frame.plot=FALSE,axes=FALSE,
        boxwex = 0.25, at = 1:3 - 0.2,
        subset = supp == "VC", col = "yellow",
        main = "Guinea Pigs' Tooth Growth",
        xlab = "Vitamin C dose mg",
        ylab = "tooth length",
        xlim = c(0.5, 3.5), ylim = c(0, 35))
boxplot(len ~ dose, data = ToothGrowth, add = TRUE,
    frame.plot=FALSE,axes=FALSE,
        boxwex = 0.25, at = 1:3 + 0.2,
        subset = supp == "OJ", col = "orange")
axis(1,at=0:4)
axis(2,at=(0:17)*2)
legend(2, 9, c("Ascorbic acid", "Orange juice"),
       fill = c("yellow", "orange"))

Theresa


Tim Clark wrote:
> Dear List,
>  
> I am creating a boxplot with two subsets, very similar to the example by Roger 
> Bivand at ?boxplot (reproduced below).  I am trying to change the labels on the 
> x-axis to have one number to cover both subsets.  I can do this in other plots 
> by using axis=FALSE followed by a separate axis() command.  I have also tried 
> variations in the names= argument but can't get it to work.  Ideally I would 
> like tickmarks on either side of each factor with the number for the level 
> centered between the two tick marks.  Any suggestions?
>  
> Thanks,
>  Tim 
>
> Example:
>
> boxplot(len ~ dose, data = ToothGrowth,
>         boxwex = 0.25, at = 1:3 - 0.2,
>         subset = supp == "VC", col = "yellow",
>         main = "Guinea Pigs' Tooth Growth",
>         xlab = "Vitamin C dose mg",
>         ylab = "tooth length",
>         xlim = c(0.5, 3.5), ylim = c(0, 35), yaxs = "i")
> boxplot(len ~ dose, data = ToothGrowth, add = TRUE,
>         boxwex = 0.25, at = 1:3 + 0.2,
>         subset = supp == "OJ", col = "orange")
> legend(2, 9, c("Ascorbic acid", "Orange juice"),
>        fill = c("yellow", "orange"))
>
>
>  Tim Clark
>
> Marine Ecologist
> National Park of American Samoa
>
>
>      
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