[R] plot() function: color transparency

[Christoph Scherber]

you will need to specify colours as RGB values and then set transparency 
via the "alpha" argument.

e.g.: color=rgb(0,0,0,alpha=0.3)

# will  give black (0,0,0) and a transparency of 30%.

Best wishes
Christoph


On 18/12/2013 23:23, capricy gao wrote:
> I checked as you suggested. However, I found that the number in those functions are the number of colors. In contrast, my number here means a specific color, for example, 2 in my code means "red", 3 in my code means "green"....
>
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> On Wednesday, December 18, 2013 1:18 PM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
>   
> On 13-12-18 2:08 PM, capricy gao wrote:
>
>> I found all the color transparency was defined with character color, or rgb color. What if I have number code and still try to modify the transparency?
>>
>> For example:
>>
>>> x=c(1:5)
>>> color=c(2,2,3,4,5)
>>> plot(x, col=color)
>>> plot(x, col=color,pch=20)
>> here I defined color by numbers, how can I modify the transparency?
> See the examples for ?palette.
>
> Duncan Murdoch
> 	[[alternative HTML version deleted]]
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