Stacked histograms like in flow cytometry

Question

I\'m trying to use ggplot or base R to produce something like the following:

Answer 1

I think it's going to be difficult to get ggplot to offset the histograms like that. At least with faceting it makes new panels, and really, this transformation makes the y-axis meaningless. (The value is in the comparison from row to row). Here's one attempt at using base graphics to try to accomplish a similar thing.

#plotting function
plotoffsethists <- function(vals, groups, freq=F, overlap=.25, alpha=.75, colors=apply(floor(rbind(col2rgb(scales:::hue_pal(h = c(0, 360) + 15, c = 100, l = 65)(nlevels(groups))),alpha=alpha*255)),2,function(x) {paste0("#",paste(sprintf("%02X",x),collapse=""))}), ...) {
    print(colors)
    if (!is.factor(groups)) {
        groups<-factor(groups)
    }
    offsethist <- function (x, col = NULL, offset=0, freq=F, ...) {
        y <- if (freq) y <- x$counts
        else 
            x$density
        nB <- length(x$breaks)
        rect(x$breaks[-nB], 0+offset, x$breaks[-1L], y+offset, col = col, ...)
    }

     hh<-tapply(vals, groups, hist, plot=F)

    ymax<-if(freq)
        sapply(hh, function(x) max(x$counts))
    else
        sapply(hh, function(x) max(x$density))
    offset<-(mean(ymax)*overlap) * (length(ymax)-1):0
    ylim<-range(c(0,ymax+offset))
    xlim<-range(sapply(hh, function(x) range(x$breaks)))
    plot.new()
    plot.window(xlim, ylim, "")
    box()
    axis(1)

    Map(offsethist, hh, colors, offset, freq=freq, ...)
    invisible(hh)
}

#sample call
par(mar=c(3,1,1,1)+.1)
plotoffsethists(my.data$V1, factor(my.data$V2), overlap=.25)