Hi Nick, I don't think it will do all that you have described, but the "dispersion" function in the plotrix package will draw an "envelope" around a line if you specify type="l" and fill=<some_color>. If you pass ulim=<some_value>, the "envelope" will extend that far from the original line. See the second example on the help page to overplot the original line.
Jim On Tue, Nov 3, 2015 at 4:35 AM, William Dunlap <wdun...@tibco.com> wrote: > > summing the Euclidean distances between points in the strands > > ... if two one strand lies within the "envelope" of another I can set > them together > > Use the max instead of the sum. > > Bill Dunlap > TIBCO Software > wdunlap tibco.com > > On Mon, Nov 2, 2015 at 9:29 AM, WRAY NICHOLAS <nicholas.w...@ntlworld.com> > wrote: > > > Hi Bill I have been doing exactly that, ie summing the Euclidean > distances > > between points in the strands Although with small sets of strands this > > technique allows me to group the strands into various sets, which I can > > assume are the same, unfortunately once I have a larger number of strands > > the distances between groups become on the same order as the distances > > within groups as so it's no longer clear cut. I have tried various > > approaches, include a kind of Monte Carlo sampling to create the distinct > > groups but the best approach seems to be a kind of "kinship" idea, where > if > > two one strand lies within the "envelope" of another I can set them > > together. But as said, creating the envelope in R is not straightforward > > > > Thanks Nick > > > > On 02 November 2015 at 16:51 William Dunlap <wdun...@tibco.com> wrote: > > > > Instead of computing the envelopes (of various radii) of paths and seeing > > if they intersect > > you could compute distances between paths and seeing if they are smaller > > than a given > > distance. Computing the distance between 2 polylines is not difficult, > > although computing > > it quickly for very long sequences of line segments is more difficult. > > > > Bill Dunlap > > TIBCO Software > > wdunlap tibco.com > > > > On Mon, Nov 2, 2015 at 7:19 AM, WRAY NICHOLAS < > nicholas.w...@ntlworld.com> > > wrote: > > > > > > > ---------- Original Message ---------- > > > From: WRAY NICHOLAS < nicholas.w...@ntlworld.com> > > > To: Duncan Murdoch < murdoch.dun...@gmail.com>, r-help > > > <r-help@missing_domain> > > > Date: at > > > Subject: Re: [R] Creating "Envelope" around a plot > > > > > > > > > Hi Dennis again, I see what you're getting at and it looks rather > groovy > > > but unfortunately what I actually need is the vector of the points on > > the > > > boundary (the graphics just being a way of checking that everything's > as > > it > > > should be) and so it rather looks like I need to do a lot of > calculating > > of > > > orthogonal vectors along straight stretches and circles round peaks > > > > > > I'm looking to do an algorithmic filtration of strands which lie within > > > the "envelope" of other strands -- your method would allow visual "by > > hand" > > > inspection but unfortunately I've got hundreds of strands to compare! > > > > > > But thanks again -- useful thoughts Nick > > > > > > > > > > > > On 02 November 2015 at 15:03 Duncan Murdoch > > > > < murdoch.dun...@gmail.com> wrote: > > > > > > > > > > > > On 02/11/2015 7:33 AM, WRAY NICHOLAS 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 > > > > > > > > The graphics system will do this for you automatically if your > > > > coordinate system has the same scale in x and y, and you use a > > > > really > > > > huge line width. For example, > > > > > > > > veca<-c(4,3,6,5,7,3,2,3,3,6,8,7)plot(veca, lwd=150, col="gray", > > > > type="l")lines(veca, lwd=2) > > > > > > > > > > > > If you want to be 1 unit away in user coordinates and the x and y > > > > scales > > > > are different, it will be a lot harder. > > > > > > > > Duncan Murdoch > > > > > > > > > > > > > > > > > > > > > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > > > > > > > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
