R help - Mar 2012 - plot points using circles filled half in red and half in blue.

I want to plot many points and want to use circles. The filling color
depends on variable a. if a=1, then not fill
if a=2 then fill with red, if a=3 then fill with blue, if a=4, fill
half with red and half with blue. Can anyone tell me how to plot the
case "a=4"? Thanks a lot

On 28/03/12 15:49, alan wrote:
> I want to plot many points and want to use circles. The filling color
> depends on variable a. if a=1, then not fill
> if a=2 then fill with red, if a=3 then fill with blue, if a=4, fill
> half with red and half with blue. Can anyone tell me how to plot the
> case "a=4"? Thanks a lot
I could be wrong --- this was known to happen once :-) --- but I
strongly doubt that there is anything ``off the peg'' that will do
what you want.  You'll have to roll your own.  I'd suggest
looking at the draw.circle() function from the plotrix package
for some ideas on how to get started.

It seems to me that for each such circle you'll have to plot
two polygons --- one for each half of the circle --- and specify
fill="red" for one and fill="blue" for the other.

It's all do-able, but is it worth the effort?  Why not fill with
green (say) when a=4?

     cheers,

         Rolf Turner

Hi Alan,
on an UTF-8 locale you can use \u25D6 and \u25D7, but you have to plot
group a=4 twice.

On Windows in a non-utf locale you can use a special Windows font:

windowsFonts(wdg2=windowsFont("Wingdings 2"))

plot(0:1,0:1)
strh<-strheight("x")/2.02
points(x = 0.5, y =
0.75+strh/2,pch="?",family="wdg2",col="red")
points(x = 0.5, y =
0.75-strh/2,pch="?",family="wdg2",col="green")

strw<-strwidth("?")
points(.4-strw/2,.7,pch="?",family="wdg2",col="red")
points(.4+strw/2,.7,pch="?",family="wdg2",col="green")

Cheers

Am 28.03.2012 04:49, schrieb alan:
> I want to plot many points and want to use circles. The filling color
> depends on variable a. if a=1, then not fill
> if a=2 then fill with red, if a=3 then fill with blue, if a=4, fill
> half with red and half with blue. Can anyone tell me how to plot the
> case "a=4"? Thanks a lot
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

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On Tue, Mar 27, 2012 at 10:49 PM, alan <alan.wu2007 at gmail.com>
wrote:
> I want to plot many points and want to use circles. The filling color
> depends on variable a. if a=1, then not fill
> if a=2 then fill with red, if a=3 then fill with blue, if a=4, fill
> half with red and half with blue. Can anyone tell me how to plot the
> case "a=4"? Thanks a lot
>
There is an example in the vignette that comes with the gridBase
package of having a pie chart for each point.

-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com

I would use the my.symbols function from the TeachingDemos package
(but then I might be a little bit biased), here is a simple example:

library(TeachingDemos)

x <- runif(25)
y <- runif(25)
z <- sample(1:4, 25, TRUE)

ms.halfcirc2 <- function(col, adj=pi/2, ...) {
	theta <- seq(0, 2*pi, length.out=300)+adj
	x <- cos(theta)
	y <- sin(theta)
	if(col==1) {
		polygon(x,y)
	} else if(col==2) {
		polygon(x,y, col='red')
	} else if(col==3) {
		polygon(x,y, col='blue')
	} else {
		polygon(x[1:150], y[1:150], border=NA, col='red')
		polygon(x[151:300], y[151:300], border=NA, col='blue')
		polygon(x,y)
	}
}

my.symbols( x, y, ms.halfcirc2, inches=1/5, add=FALSE,
	symb.plots=TRUE, col=z)


# spice it up a bit
my.symbols( x, y, ms.halfcirc2, inches=1/5, add=FALSE,
	symb.plots=TRUE, col=z, adj=runif(25, 0, pi))


Adjust things to fit better what you want.

On Tue, Mar 27, 2012 at 8:49 PM, alan <alan.wu2007 at gmail.com>
wrote:
> I want to plot many points and want to use circles. The filling color
> depends on variable a. if a=1, then not fill
> if a=2 then fill with red, if a=3 then fill with blue, if a=4, fill
> half with red and half with blue. Can anyone tell me how to plot the
> case "a=4"? Thanks a lot
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


-- 
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com

On 03/28/2012 01:49 PM, alan wrote:
> I want to plot many points and want to use circles. The filling color
> depends on variable a. if a=1, then not fill
> if a=2 then fill with red, if a=3 then fill with blue, if a=4, fill
> half with red and half with blue. Can anyone tell me how to plot the
> case "a=4"? Thanks a lot
>
Hi alan,
I think you can do this with the "floating.pie" function (plotrix).
Just
plot two equal numbers and the "pie" will be two half circles.

Jim