[R] help: selection of data

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 25.10.2008 19:19:45:

> #is this what you want?
> x <- c(-10, -5, 0, 5, 10, 15, 20)
> y <- c(10, 10, 10, -5, -6, -7, 10)
> data <- data.frame(x, y)
> subset(data, x>0 & y==min(y))

Not exactly. But maybe

y.val=which(data$y==min(data$y))
x.val=which(data$x>0)
data[x.val[x.val<y.val],]

can be used.

Regards
Petr

> 
> On Sat, Oct 25, 2008 at 12:33 PM, Martin Ballaschk <qcumba at web.de> 
wrote:
> > Hi,
> >
> > I'm not very experienced with R and struggle with data selection from 
a long
> > matrix with two columns.
> >
> > I want to cut out the data between x > 0 and min(y).
> >
> >> x <- c(-10, -5, 0, 5, 10, 15, 20)
> >> y <- c(10, 10, 10, -5, -6, -7, 10)
> >> data <- as.matrix( cbind(x, y) )
> >
> >> data
> >       x  y
> > [1,] -10 10
> > [2,]  -5 10
> > [3,]   0 10 _
> > [4,]   5 -5  |-- data interval
> > [5,]  10 -6 _|   to be selected
> > [6,]  15 -7
> > [7,]  20 10
> >
> >
> > I need that to select the interval between a time 0 and a peak that is 
the
> > minimum here to fit that interval via nls() later.
> >
> > Can anybody help? I would be very thankful for general hints how to 
select
> > data with the help of conditions.
> >
> > Cheers
> > Martin
> >
> > ______________________________________________
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> > 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.
> >
> 
> 
> 
> -- 
> Stephen Sefick
> Research Scientist
> Southeastern Natural Sciences Academy
> 
> Let's not spend our time and resources thinking about things that are
> so little or so large that all they really do for us is puff us up and
> make us feel like gods.  We are mammals, and have not exhausted the
> annoying little problems of being mammals.
> 
>                         -K. Mullis
> 
> ______________________________________________
> 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.