[R] rotate pie chart

[Paul Murrell]

Hi

gridBase won't help here (grid can't rotate traditional graphics output).

I think you have to get your hands dirty on this one, but it's not too 
hard.  Here's a function pie90() which is a tiny modification of pie(). 
  Does that do the trick?

pie90 <- function (x, labels = names(x), edges = 200, radius = 0.8, 
density = NULL,
     angle = 45, col = NULL, border = NULL, lty = NULL, main = NULL,
     ...)
{
     if (!is.numeric(x) || any(is.na(x) | x <= 0))
         stop("'x' values must be positive.")
     if (is.null(labels))
         labels <- as.character(1:length(x))
     x <- c(0, cumsum(x)/sum(x))
     dx <- diff(x)
     plot.new()
     pin <- par("pin")
     xlim <- ylim <- c(-1, 1)
     if (pin[1] > pin[2])
         xlim <- (pin[1]/pin[2]) * xlim
     else ylim <- (pin[2]/pin[1]) * ylim
     plot.window(xlim, ylim, "", asp = 1)
     nx <- length(dx)
     if (is.null(col))
         col <- if (is.null(density))
             c("white", "lightblue", "mistyrose", "lightcyan",
                 "lavender", "cornsilk")
         else par("fg")
     col <- rep(col, length.out = nx)
     border <- rep(border, length.out = nx)
     lty <- rep(lty, length.out = nx)
     angle <- rep(angle, length.out = nx)
     density <- rep(density, length.out = nx)
     for (i in 1:nx) {
         n <- max(2, floor(edges * dx[i]))
# modified line below
         t2p <- 2 * pi * seq(x[i], x[i + 1], length = n) + pi/2
         xc <- c(cos(t2p), 0) * radius
         yc <- c(sin(t2p), 0) * radius
         polygon(xc, yc, density = density[i], angle = angle[i],
             border = border[i], col = col[i], lty = lty[i])
# modified line below
         t2p <- 2 * pi * mean(x[i + 0:1]) + pi/2
         xc <- cos(t2p) * radius
         yc <- sin(t2p) * radius
         if (!is.na(lab <- labels[i]) && lab != "") {
             lines(c(1, 1.05) * xc, c(1, 1.05) * yc)
             text(1.1 * xc, 1.1 * yc, lab, xpd = TRUE, adj = ifelse(xc <
                 0, 1, 0), ...)
         }
     }
     title(main = main, ...)
     invisible(NULL)
}


Paul


Sean Davis wrote:
> You might want to look at grid graphics and gridBase.  I don't know in 
> detail how to go about what you are asking, but grid allows you to 
> rotate plots arbitrarily.  Here are a couple of links that I think are 
> useful.
> 
> http://www.stat.auckland.ac.nz/~paul/grid/grid.html
> http://www.stat.auckland.ac.nz/~paul/grid/doc/rotated.pdf
> 
> Sean
> 
> On May 24, 2005, at 10:09 AM, Lars wrote:
> 
>> hey,
>>
>> about two weeks ago i posted a question concerning the display of two 
>> piecharts on one plot. after now being able to do so, i need to rotate 
>> them. the first piece of my pie is suppose to start at 0° but at 90°. 
>> i tried several things, all failing in the end. anyone out there who 
>> has an idea?
>>
>> Lars
>>
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> 
> 
> ______________________________________________
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-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/