Hi again, Working with my real data and not with the little example i sent to the list i discovered that segm_distance function from package "pracma" does not converge to 0 in all cases, even if i increase the number of iteration to 10,000 for example. It seems that it depends on the "initialization" point - most like a minimization function.
So my thanks go to Don who's suggestion works for the real data as well without any problems - so far ;-) He suggested to use the function crossing.psp from package "spatstat". Thanks again to all who have answered and helped to solve my problem. I certainly learned few new things. Monica > From: macque...@llnl.gov > To: pisican...@hotmail.com > CC: r-help@r-project.org > Date: Wed, 23 Nov 2011 14:03:42 -0800 > Subject: Re: [R] x, y for point of intersection > > The function crossing.psp() in the spatstat package might be of use. > Here's an excerpt from its help page: > > crossing.psp package:spatstat R Documentation > Crossing Points of Two Line Segment PatternsDescription: > Finds any crossing points between two line segment patterns. > Usage: > crossing.psp(A,B) > -Don > > > -- > Don MacQueen > > Lawrence Livermore National Laboratory > 7000 East Ave., L-627 > Livermore, CA 94550 > 925-423-1062 > > > > > > On 11/22/11 12:48 PM, "R. Michael Weylandt <michael.weyla...@gmail.com>" > <michael.weyla...@gmail.com> wrote: > > >If it's a one off, the identify() function might be of help -- if you > >need something algorithmic it's harder due to floating point stuff and > >sampling frequencies. Let me know if that's the case. > > > >Michael > > > >On Nov 22, 2011, at 3:40 PM, Monica Pisica <pisican...@hotmail.com> wrote: > > > >> > >> > >> > >> Hi everyone, > >> > >> > >> > >> I am trying to get a point of intersection between a > >> polyline and a straight line ©.. and get the x and y coordinates of > >>this point. > >> For exemplification consider this: > >> > >> > >> > >> > >> > >> set.seed(123) > >> > >> > >> > >> k1 <-rnorm(100, mean=1.77, sd=3.33) > >> > >> k1 <- sort(k1) > >> > >> q1 <- rnorm(100, mean=2.37, sd=0.74) > >> > >> q1 <- sort(q1, decreasing = TRUE) > >> > >> plot(k1, q1, xlim <- c((min(k1)-5), (max(k1)+5)), > >> type="l") > >> > >> > >> > >> ya <- 2 > >> > >> xa = -5 > >> > >> yb=4 > >> > >> xb=12 > >> > >> > >> > >> lines(c(xa, xb), c(ya, yb), col = 2) > >> > >> > >> > >> # I want to get the x and y coordinates of the > >> intersection of the 2 lines ©. > >> > >> > >> > >> m <- (ya-yb)/(xa-xb) > >> > >> b <- ya-m*xa > >> > >> ln <- loess(q1~k1) > >> > >> lines(ln) > >> > >> > >> > >> It is clear that the x, y will satisfy both linear > >> equations, y = m*x + b and the ln polyline ©.. but while I can > >>visualize the > >> equation of the straight line I have problems with the polyline. I > >>will appreciate > >> any ideas to solve this problem. I thought it a trivial solution but it > >>seems I > >> cannot see it. > >> Thanks, > >> Monica > >> > >> > >> > >> ______________________________________________ > >> R-help@r-project.org mailing list > >> 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. > > > >______________________________________________ > >R-help@r-project.org mailing list > >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 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.
