Question

I’m using the party package in R to create a decision tree with some data. My dependent variable has some long strings and so the horizontal presentation of the x-axis labels means that all levels of my dependent variable are not showing.

Using the survey data from the MASS package as a trivial example, with the party package loaded:

 data(survey)
 #remove missing value
 survey2 <- subset(survey, !is.na(Clap))
 TreeResults <- ctree(Clap ~ Sex + Exer + Smoke, data=survey2)
 plot(TreeResults)

The labels I wish to rotate are for Clap, and I would like these to print at 45 degrees for each node. My real data has two terminal nodes, just like this example.

I have looked at node_barplot and I cannot see an option within there to modify the orientation of the x-axis labels.

Could someone advise how to do the label reorientation?

Thanks in advance.

Update: printing the labels up the sides as per the suggestion produced this plot:

Answer 1

Did you want something like?

plot(TreeResults,tp_args = list(beside=F))

UPDATE OP indicated this was not appropriate.

Unfortunately I cant see an easy fix. You can redefine the node_barplot() function as follows:

altbp<-function (ctreeobj, col = "black", fill = NULL, beside = NULL, 
    ymax = NULL, ylines = NULL, widths = 1, gap = NULL, reverse = NULL, 
    id = TRUE,rot=45) 
{
    getMaxPred <- function(x) {
        mp <- max(x$prediction)
        mpl <- ifelse(x$terminal, 0, getMaxPred(x$left))
        mpr <- ifelse(x$terminal, 0, getMaxPred(x$right))
        return(max(c(mp, mpl, mpr)))
    }
    y <- response(ctreeobj)[[1]]
    if (is.factor(y) || class(y) == "was_ordered") {
        ylevels <- levels(y)
        if (is.null(beside)) 
            beside <- if (length(ylevels) < 3) 
                FALSE
            else TRUE
        if (is.null(ymax)) 
            ymax <- if (beside) 
                1.1
            else 1
        if (is.null(gap)) 
            gap <- if (beside) 
                0.1
            else 0
    }
    else {
        if (is.null(beside)) 
            beside <- FALSE
        if (is.null(ymax)) 
            ymax <- getMaxPred(ctreeobj@tree) * 1.1
        ylevels <- seq(along = ctreeobj@tree$prediction)
        if (length(ylevels) < 2) 
            ylevels <- ""
        if (is.null(gap)) 
            gap <- 1
    }
    if (is.null(reverse)) 
        reverse <- !beside
    if (is.null(fill)) 
        fill <- gray.colors(length(ylevels))
    if (is.null(ylines)) 
        ylines <- if (beside) 
            c(3, 2)
        else c(1.5, 2.5)
    rval <- function(node) {
        pred <- node$prediction
        if (reverse) {
            pred <- rev(pred)
            ylevels <- rev(ylevels)
        }
        np <- length(pred)
        nc <- if (beside) 
            np
        else 1
        fill <- rep(fill, length.out = np)
        widths <- rep(widths, length.out = nc)
        col <- rep(col, length.out = nc)
        ylines <- rep(ylines, length.out = 2)
        gap <- gap * sum(widths)
        yscale <- c(0, ymax)
        xscale <- c(0, sum(widths) + (nc + 1) * gap)
        top_vp <- viewport(layout = grid.layout(nrow = 2, ncol = 3, 
            widths = unit(c(ylines[1], 1, ylines[2]), c("lines", 
                "null", "lines")), heights = unit(c(1, 1), c("lines", 
                "null"))), width = unit(1, "npc"), height = unit(1, 
            "npc") - unit(2, "lines"), name = paste("node_barplot", 
            node$nodeID, sep = ""))
        pushViewport(top_vp)
        grid.rect(gp = gpar(fill = "white", col = 0))
        top <- viewport(layout.pos.col = 2, layout.pos.row = 1)
        pushViewport(top)
        mainlab <- paste(ifelse(id, paste("Node", node$nodeID, 
            "(n = "), "n = "), sum(node$weights), ifelse(id, 
            ")", ""), sep = "")
        grid.text(mainlab)
        popViewport()
        plot <- viewport(layout.pos.col = 2, layout.pos.row = 2, 
            xscale = xscale, yscale = yscale, name = paste("node_barplot", 
                node$nodeID, "plot", sep = ""))
        pushViewport(plot)
        if (beside) {
            xcenter <- cumsum(widths + gap) - widths/2
            for (i in 1:np) {
                grid.rect(x = xcenter[i], y = 0, height = pred[i], 
                  width = widths[i], just = c("center", "bottom"), 
                  default.units = "native", gp = gpar(col = col[i], 
                    fill = fill[i]))
            }
            if (length(xcenter) > 1) 
                grid.xaxis(at = xcenter, label = FALSE)
            grid.text(ylevels, x = xcenter, y = unit(-1, "lines"), 
                just = c("center", "top"), default.units = "native", 
                check.overlap = TRUE,rot=rot)
            grid.yaxis()
        }
        else {
            ycenter <- cumsum(pred) - pred
            for (i in 1:np) {
                grid.rect(x = xscale[2]/2, y = ycenter[i], height = min(pred[i], 
                  ymax - ycenter[i]), width = widths[1], just = c("center", 
                  "bottom"), default.units = "native", gp = gpar(col = col[i], 
                  fill = fill[i]))
            }
            if (np > 1) {
                grid.text(ylevels[1], x = unit(-1, "lines"), 
                  y = 0, just = c("left", "center"), rot = 90, 
                  default.units = "native", check.overlap = TRUE)
                grid.text(ylevels[np], x = unit(-1, "lines"), 
                  y = ymax, just = c("right", "center"), rot = 90, 
                  default.units = "native", check.overlap = TRUE)
            }
            if (np > 2) {
                grid.text(ylevels[-c(1, np)], x = unit(-1, "lines"), 
                  y = ycenter[-c(1, np)], just = "center", rot = 90, 
                  default.units = "native", check.overlap = TRUE)
            }
            grid.yaxis(main = FALSE)
        }
        grid.rect(gp = gpar(fill = "transparent"))
        upViewport(2)
    }
    return(rval)
}

all this did was add rot= to the grid.text call when beside=T
then call the following:

plot(TreeResults,terminal_panel=altbp(TreeResults,ylines=1.2, gap=0.05,rot=45))

SUMMARY:

you can hack the node_barplot function a painless way to do it would be as follows:

altbp<-node_barplot
body(altbp)[[8]][[3]][[3]][[23]][[3]][[5]]<-substitute(
grid.text(ylevels, x = xcenter, y = unit(-1, "lines"), just = c("center", 
    "top"), default.units = "native", check.overlap = TRUE,rot=45)
)
plot(TreeResults,terminal_panel=altbp(TreeResults))

and use the altbp which will rotate text by 45 degrees.