# Re: [R] R cycle to calculate distances

From: Gavin Simpson <gavin.simpson_at_ucl.ac.uk>
Date: Mon, 17 Nov 2008 16:37:57 +0000

On Mon, 2008-11-17 at 07:20 -0800, P.Branco wrote:
> Sorry, it does not work.
>
> If I do a rnorm I lose the original values of my vectors, and the equation
> result must be attained by the use of the original values.

Dimitris was generating some dummy data to test that the function worked. He had to do this because you didn't provide the data to make up r1, r2, etc.

You don't need to do the calls to rnorm, just use your original data, stored in those variables/objects.

If r1, r2 already contain your data, you just need to do:

dd <- sqrt(0.723523 * outer(r1, s1, "-")^2 + 0.215518 * outer(r2, s2, "-")^2) dd

Does that work?

G

>
> Thanks,
> P.Branco
>
>
> Dimitris Rizopoulos-4 wrote:
> >
> > try this (presented only for two pairs):
> >
> > r1 <- rnorm(49)
> > r2 <- rnorm(49)
> > s1 <- rnorm(300)
> > s2 <- rnorm(300)
> >
> > dd <- sqrt(0.723523 * outer(r1, s1, "-")^2 + 0.215518 * outer(r2, s2,
> > "-")^2)
> > dd
> >
> > I hope it helps.
> >
> > Best,
> > Dimitris
> >
> > P.Branco wrote:
> >> Dear all,
> >>
> >> I am for the first time trying to work with R, but I have bumped into a
> >> problem.
> >>
> >> I have four vectors:
> >> r1 (49 values)
> >> r21 (49 values)
> >> r22 (49 values)
> >> r3 (49 values)
> >> s1 (300 values)
> >> s21 (300 values)
> >> s22 (300 values)
> >> s3 (300 values)
> >>
> >> And I would like to calculate the distances from all references (r) sites
> >> to
> >> sample (s) site, for that I wrote this equation:
> >>
> >> drs=sqrt(((0.723523*(r1[i]-s1[ii]))^2)+(((-0.215518*(r21[i]-s21[ii]))^2)+((0.518612*(r22[i]-s22[ii]))^2))+((0.283655*(r3[i]-s3[ii]))^2))
> >>
> >> Now how can I run a cycle in order to calculate the distances?
> >>
> >>
> >> P. Branco
> >>
> >
> > --
> > Dimitris Rizopoulos
> > Assistant Professor
> > Department of Biostatistics
> > Erasmus Medical Center
> >
> > Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
> > Tel: +31/(0)10/7043478
> > Fax: +31/(0)10/7043014
> >
> > ______________________________________________
> > R-help_at_r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
> >
>

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