How draw a marker at the intersection of join of two lines?
in [Matlab]
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From: W. eWatson on 14 Feb 2010 11:45 On 2/13/2010 11:35 PM, Rune Allnor wrote: > On 14 Feb, 05:33, Walter Roberson<rober...(a)hushmail.com> wrote: > >> Calculating where the intersection of the lines *is* might be simple or >> it might be computationally infeasible (for example, calculating the >> exact location of the intersection of two chaotic curves might take >> exceedingly long.) > > If the curves are represented as a set of ponts that are joined > by linear segments, there exist algorithms that report the > intersections in time proportional with the number of line segments > and the number of intersections. This can be very much faster > than brute-force searches, if only a few intersections exist. > > If, however, every segment intersects all other segments, then the > worst-case performance is O(n^2) where n is the number of line > segments. > > Just be aware that these algorithms rely heavily on dynamic search > tree data structures, so I wouldn't implement this in matlab. > > Rune > > Perhaps join would have been a better word. When I use plot in MPL, the lines are like straight path segments that are connected. It seems to me this should be easy. I have all the x,y pairs. Here's a simple example. Start at (0,0). Next are (1,1.5) and (2.2). Plot draws 2 straight line segments. I want the marker at (1,1.5). Say a yellow circle. plot(1,1.5,"yo")? In Pyton MPL, it may be almost the same, but one usually needs some qualifier like pyplot.plot(1,1.5, "yo") I have yet to find the right combo.
From: Doug Schwarz on 14 Feb 2010 18:58
In article <hl99ai$n3a$2(a)news.eternal-september.org>, "W. eWatson" <wolftracks(a)invalid.com> wrote: [snip] > Perhaps join would have been a better word. When I use plot in MPL, the > lines are like straight path segments that are connected. > > It seems to me this should be easy. I have all the x,y pairs. Here's a > simple example. Start at (0,0). Next are (1,1.5) and (2.2). Plot draws > 2 straight line segments. I want the marker at (1,1.5). Say a yellow > circle. plot(1,1.5,"yo")? > > In Pyton MPL, it may be almost the same, but one usually needs some > qualifier like pyplot.plot(1,1.5, "yo") I have yet to find the right > combo. It *is* easy, you just haven't been clear as to what you want. Since matplotlib is modeled on MATLAB I think you'll find them to be quite similar. Suppose you have two vectors, x = [0 1 2]; y = [0 1.5 2]; and you want to plot line segments only (two line segments connecting the three points) then use plot(x,y) or you can be specific about the line style with plot(x,y,'-') To plot only three small circles at the endpoints of the segments use plot(x,y,'o') and to plot both connecting lines and the little circles use plot(x,y,'o-') See the help for the plot command for more details ("help plot" or "doc plot"). Also, make sure you use single quotes in MATLAB to delimit character strings. -- Doug Schwarz dmschwarz&ieee,org Make obvious changes to get real email address. |