[R] plotting two variables with a third used for color

[JiHO]

On 2009-March-20  , at 16:23 , David Winsemius wrote:

> On Mar 20, 2009, at 3:55 PM, Altaweel, Mark R. wrote:
>
>> I have a problem where I have two columns of data that I can simply  
>> plot using:
>>
>> plot(wV[0:15,3],wY[0:15,3]).
>>
> Perhaps:
> plot(wV[0:15,3],wY[0:15,3], col = ifelse(wY[0:15,3]>0, "blue","red") )

And you could look into the package ggplot2 which gives you a legend  
and is well suited for these things.

# quick version:
qplot(wV[0:15,3], wY[0:15,3], colour=ifelse(wY[0:15,3]>0,">0","<0"))

# more explicit version, using a data.frame
dat = data.frame(v=wV[0:15,3], y=wY[0:15,3],  
sign=ifelse(wY[0:15,3]>0,">0","<0"))
ggplot(data=dat) + geom_point(aes(x=v,y=y,colour=sign))

JiHO
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http://jo.irisson.free.fr/