The problem has been solved and thankfully, it has nothing to do with Quartz and almost nothing to do with R. Before explaining briefly, I want to thank Kevin Middleton, Don MacQueen, and Jim Holtman for offering their help. This kind of support makes using tools like R even better (especially for newbies like me).
It turns out that the problem had to do with the format of the data being used to generate the plots. Although I didn't mention it in my question, the data was being read in from a formatted file (produced by someone other than me). One of the things I found impressive about R was the ease with which it read in the file. That reaction was based, in part, on being a Mathematica user and having struggled more to get it to read the same file on an earlier occasion. That may not have been such a bad thing after all. Don MacQueen was the one who asked the right questions that led to me reveal the file format as: Date Value 00-03-27 129622 00-03-28 129285 00-03-29 141328 00-03-30 130223 ..... He immediately recognized that the "Date" column was going to cause trouble unless R was given more explicit instructions about how to treat it viz., as a string! In lieu of that (and this is the not so good part), R decides to be "helpful" and treat that column as integers. Probably (I haven't done the detailed analysis) that led to each triple of integers being computed as a pair (the 00- being treated as a zero) which led to each "dot" in the plot being displayed as a pair of dots, with further confusion apparently causing R to render the "dots" as something more complex (e.g., "knots"). You get the idea. Whether to interpret certain values as numbers or strings is an old I/O gotcha. What had me fooled was that the plot *looked* correct, when compared to the Mathematica plot, but it was taking far too much time to render on PPC Quartz! --njg Neil Gunther wrote: > I just tried rendering a plot of 166 data point (time series) on my PPC > mac, > and compared it with the same data rendered by Mathematica. The R > plotting is very slow to paint and repaint, compared to Mathematica. > This also makes it extremely awkward to use in other documentation such > as pdfLatex. > > On closer inspection, it looks like the Mathematica plot is just a > polyline, while in R it is a B-spline with each marker consisting of 24 > B-splines knotted together. Moreover, the spline joints are rounded, > which requires computing two circles and intersecting them 26 times at > each bend. > > Is there some reason why the point-markers are not just drawn as circles > or squares, instead of doing these complicated and time-consuming knots? > > -- njg > ________________________________________________________________________ > > PERFORMANCE DYNAMICS COMPANY http://www.perfdynamics.com/ > ________________________________________________________________________ ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
