[FORGED] Re: draw stripes in a circle in R

Envoy? depuis mon appareil Samsung

-------- Message d'origine --------
De : Rolf Turner <r.turner at auckland.ac.nz>
Date : 14/06/2017  22:53  (GMT+01:00)
? : David Winsemius <dwinsemius at comcast.net>
Cc : r-help at r-project.org
Objet : Re: [R] [FORGED] Re:&nbsp; draw stripes in a circle in R

On 15/06/17 05:29, David Winsemius wrote:

On Jun 14, 2017, at 10:18 AM, David Winsemius <dwinsemius at comcast.net> wrote:

On Jun 14, 2017, at 9:46 AM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote:

I don't see a question. If your question is whether R supports pattern fills, AFAIK it does not. If that is not your question, ask one.
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On June 14, 2017 7:57:41 AM PDT, jean-philippe <jeanphilippe.fontaine at gssi.infn.it> wrote:

dear R users,

I would like to fill a circle with yellow stripes instead of a uniform
yellow color. To draw the circle I used the following command after
having loaded the (very nice !) plotrix library :

I finally understood the question and it needs a hack to the draw.circle function in plotrix since the angle and density arguments don't get passed in:

First get code for draw.circle:

------

draw.circle   # then copy to console and edit

draw.circle2  <- function (x, y, radius, nv = 100, border = NULL, col = NA, lty = 1,
                            density=NA, angle=45,  lwd = 1 )
{
     xylim <- par("usr")
     plotdim <- par("pin")
     ymult <- getYmult()
     angle.inc <- 2 * pi/nv
     angles <- seq(0, 2 * pi - angle.inc, by = angle.inc)
     if (length(col) < length(radius))
         col <- rep(col, length.out = length(radius))
     for (circle in 1:length(radius)) {
         xv <- cos(angles) * radius[circle] + x
         yv <- sin(angles) * radius[circle] * ymult + y
         polygon(xv, yv, border = border, col = col, lty = lty, density=density, angle=angle,
                 lwd = lwd)
     }
     invisible(list(x = xv, y = yv))
}

Now run your call to pdf with draw.circle2 instead of draw.circle.

This is just idle curiosity, since I'm not really able to contribute
anything useful, but I can't resist asking:  When I try to run the OP's
code I get an error:

Error in alpha("red", 0.4) : could not find function "alpha".

Sorry for the lack of precision, alpha is just to add some transparency to the color. This alpha parameter ranges from 0 fully transparent to 1, full color.I don't remember having loaded any package to use this function, I think it is there in base R.
Why does this (apparently) not happen to anyone else?  Why does the
universe pick on *me*?  What is the function "alpha()"?  Where is it to
be found?

Searching on "alpha" is of course completely unproductive; there are far
too many (totally irrelevant) instances.

cheers,

Rolf

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