Try this :
    >it<-seq(0,2*pi, l=100)
    >xt<-r*cos(it)
    >yt<-r*sin(it)
    >points(xt,yt,type="l",col="blue")

a circle of radium r is define by
   xt=r*cos(t)
   yt=r*sin(t) 

Justin BEM
Elève Ingénieur Statisticien Economiste
BP 294 Yaoundé.
Tél (00237)9597295.



----- Message d'origine ----
De : Xiaomei Ma <xiaomei.ma@yale.edu>
À : R-help@stat.math.ethz.ch
Envoyé le : Mardi, 7 Novembre 2006, 6h11mn 27s
Objet : [R] Draw a circle with a given radius in an existing map


I have drawn a map in which the X and Y axes are latitude and 
longitude. Now I need to draw one circle on the map - the center is a 
point with specific latitude and longitude, but the challenge is that 
the radius is in miles. Is there a way to do this? I'd very much 
appreciate your response.

XM

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