Right on. The convenience of slurping up data with read.table() and the nearly expected plot caused me to overlook that V2 was read in as a factor. I also had quite a few NAs which may have contributed to the problem.
Thanks On Mon, 29 Mar 2004, Duncan Murdoch wrote: > On Mon, 29 Mar 2004 14:06:36 -0800 (PST), Clint Bowman > <[EMAIL PROTECTED]> wrote : > > >I have a 2 by 226200 table, conveniently read in by read.table(), which > >exhibits some strange behavior when plotted by plot(V1,V2). The general > >pattern for the range of windspeeds, [0<V1<50] is as expected -- the wind > >gust falls in the interval [V1<V2<65] except for certain values of V2. > >For V2 == c(15,26,37,48,59), the V2 values are positioned at one-tenth of > >the V1 (i.e., as if I had issued the command plot(0.1*V1,V2) for just > >those values of V2 -- see attached plot, test.png). The only other values > >of V2 in the range, 4 and 70, also seem to be affected but aren't well > >enough represented to show up clearly on the plot. > > > >However, if I plot(ws$V1[ws$V2==48],ws$V2[ws$V2==48]), I see the second > >attachment, test2.png, which confirms that the wind speed (V1) really > >should be positioned where one would expect. I haven't seen any messages > >covering this behaviour and so am looking for an explanation. > > I can't quite see how it would generate the symptoms you saw, but a > common source of oddities is that data is read as factors rather than > as numeric values. You can see the difference using the str() > function, e.g. > > > str(x) > num [1:10] -0.4897 0.6804 0.6979 -0.1203 -0.0428 ... > > str(as.factor(x)) > Factor w/ 10 levels "-1.65972758..",..: 4 7 8 5 6 9 2 10 3 1 > > I'd check your V1 and V2. > > Duncan Murdoch > -- Clint Bowman INTERNET: [EMAIL PROTECTED] Air Quality Modeler INTERNET: [EMAIL PROTECTED] Department of Ecology VOICE: (360) 407-6815 PO Box 47600 FAX: (360) 407-7534 Olympia, WA 98504-7600 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html