[R] How can I create transparant colour

[Prof Brian Ripley]

Well, if it is transparent then you will not see it: I presume you mean 
translucent (aka semi-transparent).  With 50% opacity you could use

red <- rgb(0x9E, 0x47, 0x70, 127, max=255)
polygon(xvalue1,yvalue1,col=red,border=red)

See ?rgb.

You can also specify a translucent colour as e.g. "#9E47707F", but that 
seems less intuitive.


On Thu, 4 Dec 2008, Dr. Alireza Zolfaghari wrote:

> Hi list,
> Does any one know how I can make the red colour transparant?
>
> #########################
> par()
> #Set up blank plot to remove plot border type lty="n"
> xvalue1<- c(1,2,2,1)
> xvalue2<- c(1,3,3,1)
> yvalue1<- c(0,0,22,22)
> yvalue2<- c(0,0,44,44)
> plot(c(min(xvalue2),max(xvalue2)),c(min(yvalue2),max(yvalue2)),type="n",xaxt="n",yaxt="n",xlab="",ylab="Loss
> in ?m",yaxs="i",xaxs="r")
> polygon(xvalue2,yvalue2,col="#A8B50A",border="#A8B50A")
> polygon(xvalue1,yvalue1,col="#9E4770",border="#9E4770")
> #########################
>
> regards,
> Alireza
>
> 	[[alternative HTML version deleted]]
>
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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