How do you make a comparative stem and leaf plot in R? The data on one side is
c(5.9, 7.2, 7.3, 6.3, 8.1, 6.8, 7.0, 7.6, 6.8, 6.5, 7.0, 6.4, 7.9, 9.0, 8.2, 8.7, 7.8, 9.7, 7.4, 7.7, 9.7, 7.8, 7.7, 11.6, 11.3, 11.8, 10.7) and the data on the other side is
c(6.1, 5.8, 7.8, 7.1, 7.2, 9.2, 6.6, 8.3, 7.0, 8.3, 7.8, 8.1, 7.4, 8.5, 8.9, 9.8, 9.7, 14.1, 12.6, 11.2) I have already assigned each to either x[1] or x[2]. I have tried making two stem and leaf plots and then combining them but that does not work.
2 Answers
Have a look at stem.leaf.backback of the aplpack package. It sounds like that may be what you are looking for.
> a <- c(5.9, 7.2, 7.3, 6.3, 8.1, 6.8, 7.0, 7.6, 6.8, 6.5, 7.0, 6.4, 7.9, 9.0, 8.2, 8.7, 7.8, 9.7, 7.4, 7.7, 9.7, 7.8, 7.7, 11.6, 11.3, 11.8, 10.7) > b <-c(6.1, 5.8, 7.8, 7.1, 7.2, 9.2, 6.6, 8.3, 7.0, 8.3, 7.8, 8.1, 7.4, 8.5, 8.9, 9.8, 9.7,14.1, 12.6, 11.2) > stem.leaf.backback(a,b) _________________________________ 1 | 2: represents 1.2, leaf unit: 0.1 a b _________________________________ | 5* | 1 9| 5. |8 1 3 43| 6* |1 2 6 885| 6. |6 3 11 43200| 7* |0124 7 (6) 988776| 7. |88 9 10 21| 8* |133 (3) 8 7| 8. |59 8 7 0| 9* |2 6 6 77| 9. |78 5 | 10* | 4 7| 10. | 3 3| 11* |2 3 2 86| 11. | | 12* | _________________________________ HI: 12.6 14.1 n: 27 20 _________________________________ Setting the m parameter to 1 gives:
> stem.leaf.backback(a,b,m=1) ___________________________________________ 1 | 2: represents 1.2, leaf unit: 0.1 a b ___________________________________________ 1 9| 5 |8 1 6 88543| 6 |16 3 (11) 98877643200| 7 |012488 9 10 721| 8 |13359 (5) 7 770| 9 |278 6 4 7| 10 | 3 863| 11 |2 3 | 12 |6 2 ___________________________________________ HI: 14.1 n: 27 20 ___________________________________________ The basic stem function has no support for this. It would be easier to do a histogram as @pbible pointed out (although, not much easier if you want them back to back). But you could do
#sample data x<-list() x[[1]]<-c(5.9, 7.2, 7.3, 6.3, 8.1, 6.8, 7.0, 7.6, 6.8, 6.5, 7.0, 6.4, 7.9, 9.0, 8.2, 8.7, 7.8, 9.7, 7.4, 7.7, 9.7, 7.8, 7.7, 11.6, 11.3, 11.8, 10.7) x[[2]]<-c(6.1, 5.8, 7.8, 7.1, 7.2, 9.2, 6.6, 8.3, 7.0, 8.3, 7.8, 8.1, 7.4, 8.5, 8.9, 9.8, 9.7, 14.1, 12.6, 11.2) #specify common breaks brx <- pretty(range(unlist(x)), n = nclass.Sturges(unlist(x)),min.n = 1) #calculate bins h1 = hist(x[[1]], breaks=brx, plot=FALSE) h2 = hist(x[[2]], breaks=brx, plot=FALSE) #draw plot(NA,NA,type="n", xlab="", ylab="", xlim=range(c(-h1$counts, h2$counts)), ylim=range(brx), xaxt="n" ) rect(-h1$counts, brx[-1], 0, brx[-length(brx)], col="blue") rect(0, brx[-1], h2$counts, brx[-length(brx)], col="red") axis(1, at=axTicks(side=1), labels=abs(axTicks(side=1))) which gives you
And if it really needs to be stem and leaf style, here's a fragile attempt
x<-list() x[[1]]<-c(5.9, 7.2, 7.3, 6.3, 8.1, 6.8, 7.0, 7.6, 6.8, 6.5, 7.0, 6.4, 7.9, 9.0, 8.2, 8.7, 7.8, 9.7, 7.4, 7.7, 9.7, 7.8, 7.7, 11.6, 11.3, 11.8, 10.7) x[[2]]<-c(6.1, 5.8, 7.8, 7.1, 7.2, 9.2, 6.6, 8.3, 7.0, 8.3, 7.8, 8.1, 7.4, 8.5, 8.9, 9.8, 9.7, 14.1, 12.6, 11.2) X<-stack(setNames(x, c("a","b"))) brx <- pretty(range(X$values), n = nclass.Sturges(X$values),min.n = 1) X$stem <- factor(brx[cut(unlist(x), breaks=brx, include.lowest=T, labels=F)], levels=brx[-length(brx)]) X$leaf <- as.integer(X$values %% 1 *10) max.leaf.width <- 2*with(aggregate(leaf~ind+stem, X, length), tapply(leaf, ind, max)) fmt<-paste0("%", max.leaf.width[1],"s | %2s | %-", max.leaf.width[2],"s") va<-with(subset(X, ind=="a"), tapply(leaf, stem, function(x) paste(rev(sort(x)), collapse=" "))) vb<-with(subset(X, ind=="b"), tapply(leaf, stem, function(x) paste(sort(x), collapse=" "))) va[is.na(va)]<-"" vb[is.na(vb)]<-"" cat(paste(sprintf(fmt, va, levels(X$stem), vb), collapse="\n"), "\n") Which produces
9 | 5 | 7 7 7 5 4 2 0 0 | 6 | 0 0 5 9 7 7 7 7 5 4 2 2 | 7 | 0 2 4 7 7 6 1 0 0 | 8 | 0 3 3 5 9 6 6 | 9 | 1 6 8 6 | 10 | 8 5 3 | 11 | 1 | 12 | 5 | 13 | | 14 | 0 
