Just to give you more options to choose from, Here is a variation on Gabor's solution:
with(example.df[c(TRUE,FALSE,FALSE,FALSE,FALSE),], { plot(DSR1 ~ StartDate, type = "b", ylim = c(0.3, 0.9)) points(DSR2 ~ StartDate, type = "b", pch = 3) }) Move the TRUE around and you get the different sequences and you don't need to know the number of rows. On a similar note you could try: plot(DSR1 ~ StartDate, type='b', ylim=c(0.3,0.9), pch=c(1,rep(NA,4))) points(DSR2 ~ StartDate, type='b', pch=c(3,rep(NA,4))) You will still have the lines between all the points, but only every 5th point. Hope this helps, -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare [EMAIL PROTECTED] (801) 408-8111 > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Jessi Brown > Sent: Wednesday, February 20, 2008 6:57 PM > To: Gabor Grothendieck > Cc: r-help@r-project.org > Subject: Re: [R] plotting every ith data point? > > Thanks for the ideas so far, Gabor and Phil. > > I was hoping to find a solution that didn't depend on > building another data frame, but if that's the easiest way, I > can certainly do it through that route. At least your > solutions involve fewer lines of code than I had devised for > extracting the desired rows (am still a newbie at data > manipulation with R!). > > cheers, Jessi > > On Wed, Feb 20, 2008 at 7:08 PM, Gabor Grothendieck > <[EMAIL PROTECTED]> wrote: > > Try this: > > > > ix <- seq(1, nrow(example.df), 5) > > with(example.df[ix,], { > > plot(DSR1 ~ StartDate, type = "b", ylim = c(0.3, 0.9)) > > points(DSR2 ~ StartDate, type = "b", pch = 3) > > }) > > > > > > > > > > On Wed, Feb 20, 2008 at 6:57 PM, Jessi Brown > <[EMAIL PROTECTED]> wrote: > > > Hello, fellow R enthusiasts. > > > > > > Ok, I've been racking my brain about this small issue, > and between > > > searching the help archives and reading through the > plot-related > > > documentation, I can't figure out how to achieve my desired > endpoint > > > without some ugly, brute force coding. > > > > > > What I would like to do is make a plot in which only a > subset of my > > > data are plotted, but in regular intervals, such as every > 5th point > > > along the sequence. Is anyone aware of a built-in > function in plot > > or > a related graphing family that can do this, or > alternatively, a > > simple > way to extract the desired rows from my original > dataframe? > > I want to > do this because I want to plot multiple series > of points > > with their > confidence intervals (arrows), and even if I specify > > type="b," the > output ends up looking like just a series > of crowded points. > > > > > > For example, if you try making the plot below, you will > see how > > > crowded two lines look without error bars: > > > > > > > example.df<-data.frame(StartDate=(94:157), DSR1=seq(0.4, 0.8, > > length.out=64), DSR2=seq(0.3, 0.9, length.out=64)) > > > > plot(example.df$StartDate, example.df$DSR1, type="b", > ylim=c(0.3,0.9)) > > > > points(example.df$StartDate, example.df$DSR2, type="b", > pch=3) > > > > Any ideas for an elegant solution to my dilemma? > > > > > > Thanks in advance for any help. > > > > > > cheers, Jessi Brown > > > > > > Ph.D. student > > > Program in Ecology, Evolution, and Conservation Biology > > > University of Nevada, Reno > > > > ______________________________________________ > > > 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. > ______________________________________________ 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.