plot() function: color transparency

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"....

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