[R] dotchart with log scale?

[Johannes Hüsing]

> Dear all,
> I would like to draw a dot chart on a log scale.
> What is the syntax for this? A barchart may use
> log="x", but trying this with dotchart() leads
> to an error message.

ok, I extended dotchart() with a log option.
The main reason I am sticking to dotchart() is
adjusting of axes with respect to long text
labels.

This is the definition I am using now:


mydotchart <-
  function (x, labels = NULL, groups = NULL, gdata = NULL, cex = par("cex"),
            pch = 21, gpch = 21, bg = par("bg"), color = par("fg"), gcolor
= par("fg"),
            lcolor = "gray", xlim = range(x[is.finite(x)]), main = NULL,
###                                   new option
            xlab = NULL, ylab = NULL, log=FALSE, ...) {
    opar <- par("mai", "cex", "yaxs")
    on.exit(par(opar))
    par(cex = cex, yaxs = "i")
    n <- length(x)
    if (is.matrix(x)) {
      if (is.null(labels))
        labels <- rownames(x)
      if (is.null(labels))
        labels <- as.character(1:nrow(x))
      labels <- rep(labels, length.out = n)
      if (is.null(groups))
        groups <- col(x, as.factor = TRUE)
      glabels <- levels(groups)
    }
    else {
      if (is.null(labels))
        labels <- names(x)
      glabels <- if (!is.null(groups))
        levels(groups)
    }
    plot.new()
    linch <- if (!is.null(labels))
      max(strwidth(labels, "inch"), na.rm = TRUE)
    else 0
    if (is.null(glabels)) {
      ginch <- 0
      goffset <- 0
    }
    else {
      ginch <- max(strwidth(glabels, "inch"), na.rm = TRUE)
      goffset <- 0.4
    }
    if (!(is.null(labels) && is.null(glabels))) {
      nmai <- par("mai")
      nmai[2] <- nmai[4] + max(linch + goffset, ginch) + 0.1
      par(mai = nmai)
    }
    if (is.null(groups)) {
      o <- 1:n
      y <- o
      ylim <- c(0, n + 1)
    }
    else {
      o <- sort.list(as.numeric(groups), decreasing = TRUE)
      x <- x[o]
      groups <- groups[o]
      color <- rep(color, length.out = length(groups))[o]
      lcolor <- rep(lcolor, length.out = length(groups))[o]
      offset <- cumsum(c(0, diff(as.numeric(groups)) != 0))
      y <- 1:n + 2 * offset
      ylim <- range(0, y + 2)
    }
###                                       instead of log=""
    plot.window(xlim = xlim, ylim = ylim, log = ifelse(log, "x", ""))
    lheight <- par("csi")
    if (!is.null(labels)) {
      linch <- max(strwidth(labels, "inch"), na.rm = TRUE)
      loffset <- (linch + 0.1)/lheight
      labs <- labels[o]
      mtext(labs, side = 2, line = loffset, at = y, adj = 0,
            col = color, las = 2, cex = cex, ...)
    }
    abline(h = y, lty = "dotted", col = lcolor)
    points(x, y, pch = pch, col = color, bg = bg)
    if (!is.null(groups)) {
      gpos <- rev(cumsum(rev(tapply(groups, groups, length)) +
                         2) - 1)
      ginch <- max(strwidth(glabels, "inch"), na.rm = TRUE)
      goffset <- (max(linch + 0.2, ginch, na.rm = TRUE) + 0.1)/lheight
      mtext(glabels, side = 2, line = goffset, at = gpos, adj = 0,
            col = gcolor, las = 2, cex = cex, ...)
      if (!is.null(gdata)) {
        abline(h = gpos, lty = "dotted")
        points(gdata, gpos, pch = gpch, col = gcolor, bg = bg,
               ...)
      }
    }
    axis(1)
    box()
    title(main = main, xlab = xlab, ylab = ylab, ...)
    invisible()
}

Many thanks for your attention.