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A while back I posted the following question:
I am running S-PLUS 8.0 and have a bar chart question. Most of my bars are under a certain height, say 20, but one goes all the way up to 70. I would like to have the Y-axis stop at 20 so that most of the bars are not compressed. Is there a way to break the one tall bar to indicate that it goes off the scale? The attached image shows what I am trying to do. Any ideas out there?
Bill Dunlap at Insightful provided the following solution, which worked for me. Being new to SPlus programming, I added some comments to the code to keep track of what was going on. Thanks Bill.
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x<-c(21,23,25,21,76,79,10)
my.barplot(x, ylim=c(0,30))
my.barplot <- function(x, ..., ylim = c(0,max(x))) {
b <- barplot(pmin(x,ylim[2]) , ..., ylim = ylim)
#pmin above truncates the higher values, in this case to 30
big <- x > ylim[2] #Gives a list of T & F values, where T = bigger than 30
if(any(big)) {
# label tops of truncated bars
# b contains the coordinates of the center of the x-axis of the bars.
# The first two arguments below are the x and y coordinates for the text.
# par("usr") gives the max and min coords for the plot, for the x & y axis; [4] is the y max
# par("cxy") gives the width and height if characters; [2] is the height
# xpd = True allow stuff to be drawn outside the plot
text(b[big], rep(par("usr")[4], sum(b)) + par("cxy")[2], as.character(x[big]), xpd = TRUE)
# overwrite truncated bars with parallelogram
# with given half height and half width.
halfheight <- par("cxy")[2] * 0.7
halfwidth <- (b[2] - b[1])/2 * 0.95 # if 1 bar, use mean(par("usr")[1:2])*.8?
ybreak <- 0.8 * ylim[2]
for(i in which(big)) {
bi <- b[i]
polygon(col = par("bg"), border=FALSE, x = c(bi - halfwidth, bi + halfwidth, bi +
halfwidth, bi - halfwidth), y = c(ybreak - halfheight,
ybreak, ybreak + 2 * halfheight, ybreak + halfheight))
segments(c(bi - halfwidth, bi - halfwidth), c(ybreak - halfheight,
ybreak + halfheight), c(bi + halfwidth, bi + halfwidth),
c(ybreak, ybreak + 2 * halfheight))
}
}
}
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Jim Daley Coldwater Fisheries Unit Leader NYSDEC Bureau of Fisheries 625 Broadway, 5th Floor Albany, NY 12233-4753 jgdaley@gw.dec.state.ny.us
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