[R] Creating "Envelope" around a plot

Greg Snow
Thu, 05 Nov 2015 18:01:13 -0000

Look at the polylineoffset function in the polyclip package.  It looks
like it does what you are asking for.

On Mon, Nov 2, 2015 at 5:33 AM, WRAY NICHOLAS
<nicholas.wray at ntlworld.com> wrote:
> Hi  I am plotting various strands of information, and I want to create an
> "envelope" around each line, so that the locus of the envelope is
the boundary
> points no more than a fixed maximum distance from the plotted line, a bit
like
> drawing a larger rectangle with paralle sides and curved compass corners
around
> a smaller rectangle.  Obviously I can work out how to do this in code
> (eventually) but I suspect it would take me a while and i was wondering
whether
> there was some R function which I don't know about which creates sets
of of
> points at a given maximal distance
>
> the lines are simple vectors, ie like this noddy example
>
> veca<-c(4,3,6,5,7,3,2,3,3,6,8,7)
> plot(veca,type="l",lwd=2)
>
> then I want to plot the locus of the boundary of all points no more than
(say) 1
> unit from the line  I imagine that one would have to provide a larger set
of
> interpolated points between the actual points of veca, but I can do that no
> problem
>
> I'd be grateful if anyone out there in the R-ethervoid has any ideas
>
> Thanks, Nick Wray
>         [[alternative HTML version deleted]]
>
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--
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com