[R] Calculate an equation

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 20.11.2008 16:15:44:

> 
> I tried to do some cycles using the ?for? function, but then I had to 
make
> multiple ?for?s and it didn?t work. One of the major problems is that I
> don?t know how to use the summation function on R.

I did not find function summation. From your description I think you could 
look to cumsum or maybe sum or maybe to some other functions like rowSums. 
But if you want some more elaborated help first you shall provide some 
insight how your data look like. Try to make a simple example with fake 
data which everybody can reproduce.

Regards
Petr

> 
> Best regards,
> 
> P.Branco
> 
> stephen sefick wrote:
> > 
> > What have you tried so far?
> > 
> > On Thu, Nov 20, 2008 at 7:40 AM, P.Branco <pjlbranco at yahoo.com> wrote:
> >>
> >> Dear all,
> >>
> >> I was wondering if you could help me with the following.
> >>
> >> I want to do calculate this equation:
> >>
> >> Ps(t)=  ($B-t(B_(r=1)^N Xtr* 1/?drs)/($B-t(B_(r=1)^N 1/?drs)
> >>
> >> Ps(t) ? Probability that taxon t will occur at site s (300 sites s)
> >> N ? Number of sites = from 1 to 49
> >> Xtr ? Value for taxon t at site r (I have this information in a 
table, 40
> >> taxa (columns) t, 49 sites r)
> >> drs ? Distance from site r to site s (this information is on a table, 
s
> >> sites (columns))
> >>
> >> I thought that R would be the software to use, but I am experiencing 
some
> >> difficulties
> >>
> >> Thanks to everyone,
> >> P.Branco
> >>
> >> --
> >> View this message in context:
> >> http://www.nabble.com/Calculate-an-equation-tp20600332p20600332.html
> >> Sent from the R help mailing list archive at Nabble.com.
> >>
> >> ______________________________________________
> >> 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.
> >>
> > 
> > 
> > 
> > -- 
> > 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.
> > 
> > 
> 
> -- 
> View this message in context: 
http://www.nabble.com/Calculate-an-equation-
> tp20600332p20603107.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> 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.