Update to plotTree.boxplot for formula method

In the documentation to the new function plotTree.boxplot I noted:

“\code{x} can also be supplied as a formula, though in that case the factor levels need to be provided in the cladewise order of the tips in \code{tree}.”

What I didn't note is that if this is not done, then the result will be incorrect without any error being reported. This is because the formula provided by the user is passed directly to the function boxplot without any feedback to the tree plotter.

What I realized is that one thing that I could do was first run boxplot.formula with plot=FALSE which (invisibly) returns a list containing the order of the plotted boxes. Then I could pass that argument to plotTree using tips. Finally, I could re-run boxplot with plot=TRUE. If the order of the factor in formula is a valid cladewise order of the tips of the tree then the tree & boxplot will plot fine. If it is not, say if we randomize the levels of our factor, then the edges of the tree will cross when plotting.

Here is what I mean.

Here's our tree & data applied using the basic method:

library(phytools)
tree

## 
## Phylogenetic tree with 26 tips and 25 internal nodes.
## 
## Tip labels:
##  Z, Y, X, W, V, U, ...
## 
## Rooted; includes branch lengths.

x[1:30] ## first 30 elements of x

##            Z            Z            Z            Z            Z 
##  1.481718482  1.999288805  1.244922289  1.465959575  1.439767680 
##            Y            Y            Y            Y            Y 
##  1.014757614  1.937999703  0.728102930  0.690196494 -0.081170095 
##            X            X            X            X            X 
##  1.506780336  1.680023687  1.337899661  0.300120161  0.706118301 
##            W            W            W            W            W 
## -0.615363928  1.062724934 -0.556182889 -1.070714742 -1.271925923 
##            V            V            V            V            V 
## -1.228228110 -0.957836899 -0.617736401  0.300541684 -0.161967102 
##            U            U            U            U            U 
##  1.722133482  1.169447096  0.624685958  2.154831186  0.009577268

plotTree.boxplot(tree,x) ## basic method

Now let's try the formula method in which our factor is in the order of our tree's tip labels:

spp<-factor(names(x),levels=reorder(tree)$tip.label)
plotTree.boxplot(tree,x~spp)

Next, we can flip the order of our factor levels. This is still a valid cladewise order so this should work fine:

spp<-factor(names(x),levels=tree$tip.label[Ntip(tree):1])
spp

##   [1] Z Z Z Z Z Y Y Y Y Y X X X X X W W W W W V V V V V U U U U U T T T T T
##  [36] S S S S S R R R R R Q Q Q Q Q P P P P P O O O O O N N N N N M M M M M
##  [71] L L L L L K K K K K J J J J J I I I I I H H H H H G G G G G F F F F F
## [106] E E E E E D D D D D C C C C C B B B B B A A A A A
## Levels: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

plotTree.boxplot(tree,x~spp)

Ladderized - also a valid cladewise order:

spp<-factor(names(x),untangle(ladderize(tree),"read.tree")$tip.label)
spp

##   [1] Z Z Z Z Z Y Y Y Y Y X X X X X W W W W W V V V V V U U U U U T T T T T
##  [36] S S S S S R R R R R Q Q Q Q Q P P P P P O O O O O N N N N N M M M M M
##  [71] L L L L L K K K K K J J J J J I I I I I H H H H H G G G G G F F F F F
## [106] E E E E E D D D D D C C C C C B B B B B A A A A A
## Levels: V U W S R T Q P L K J I M O N Y X Z B A C E D H G F

plotTree.boxplot(tree,x~spp)

(Note that we didn't ladderize our input tree for plotTree.boxplot - however the plotted tree will be ladderized.)

Finally, randomize them. This will not (generally speaking) result in a valid cladewise order:

spp<-factor(names(x),levels=sample(tree$tip.label))
spp

##   [1] Z Z Z Z Z Y Y Y Y Y X X X X X W W W W W V V V V V U U U U U T T T T T
##  [36] S S S S S R R R R R Q Q Q Q Q P P P P P O O O O O N N N N N M M M M M
##  [71] L L L L L K K K K K J J J J J I I I I I H H H H H G G G G G F F F F F
## [106] E E E E E D D D D D C C C C C B B B B B A A A A A
## Levels: N L D C Q F J E T V A G P O B Y U K M S R H X W Z I

plotTree.boxplot(tree,x~spp)

This makes it much easier to see if we have a problem using the formula method.

The update can be seen here.