problem-4.12

problem-4.12  As the data is stored in a list, the boxplots are produced without any additional work:
> boxplot(u2)
    
However, we see that the titles are not legible. We can plot the titles along the side and give enough room for them to print with the commands:
> par(mar=c(5,15,4,2))          # increase to 15 from default 4
> boxplot(u2, las=2, horizontal=TRUE)
> par(mar=c(5,4,4,2))           # restore to original settings
    
The mean and median for each album can be found using sapply():
> sapply(u2,mean)
> sapply(u2,median)
    
Comparisons can be made by subtracting the two. Finally, after unlisting we can sort to find the lengths:
> rev(sort(unlist(u2)))[1:3]
                 Zooropa. Lemon                Zooropa. Zooropa
                            416                             390
Rattle & Hum. All I Want Is You
                            390