[R] plotting every ith data point?

[Greg Snow]

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
greg.snow at imail.org
(801) 408-8111
 
 

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Jessi Brown
> Sent: Wednesday, February 20, 2008 6:57 PM
> To: Gabor Grothendieck
> Cc: r-help at 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 
> <ggrothendieck at gmail.com> 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 
> <jessilbrown at gmail.com> 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 at 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.
> >  >
> >
> 
> ______________________________________________
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> PLEASE do read the posting guide 
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> and provide commented, minimal, self-contained, reproducible code.
>