[R] manipulating "by" lists and "ave()" functions
Berry Boessenkool
berryboessenkool at hotmail.com
Sat Jul 9 15:44:29 CEST 2011
Maybe I'm missing something, but in what package do I find that function?
> simplify2array(b)
Fehler: konnte Funktion "simplify2array" nicht finden
# Function wasn't found
> help.search("simplify2array")
No help files found with alias or concept or title matching ‘simplify2array’ using fuzzy matching.
A (very) short google search didn't help me either...
> sessionInfo()
R version 2.12.2 (2011-02-25)
Platform: i386-pc-mingw32/i386 (32-bit)
locale:
[1] LC_COLLATE=German_Germany.1252 LC_CTYPE=German_Germany.1252 LC_MONETARY=German_Germany.1252 LC_NUMERIC=C LC_TIME=German_Germany.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] lattice_0.19-17
loaded via a namespace (and not attached):
[1] grid_2.12.2 tools_2.12.2
Thanks ahead,
Berry
-------------------------------------
Berry Boessenkool
Potsdam
-------------------------------------
----------------------------------------
> From: ivo.welch at gmail.com
> Date: Fri, 8 Jul 2011 16:22:18 -0700
> To: wdunlap at tibco.com
> CC: r-help at stat.math.ethz.ch
> Subject: Re: [R] manipulating "by" lists and "ave()" functions
>
> It does!! why is this function not mentioned in the "See also" docpage for
> "by" (and friends)??? (Also, "ave" should be mentioned there, too.)
>
> do I post this suggestion to add it to r-devel, or is there a way to find
> out who is in charge of the docpage for "by"?
>
> regards,
>
> /iaw
>
>
> On Fri, Jul 8, 2011 at 4:17 PM, William Dunlap <wdunlap at tibco.com> wrote:
>
> > Q1. simplify2array(b) gives the transpose of what
> > I think you want.
> >
> > Bill Dunlap
> > Spotfire, TIBCO Software
> > wdunlap tibco.com
> >
> > > -----Original Message-----
> > > From: r-help-bounces at r-project.org
> > > [mailto:r-help-bounces at r-project.org] On Behalf Of ivo welch
> > > Sent: Friday, July 08, 2011 3:43 PM
> > > To: r-help
> > > Subject: [R] manipulating "by" lists and "ave()" functions
> > >
> > > dear R wizards---more ignorance on my part, exacerbated by too few
> > > examples in the function documentations.
> > >
> > > > d <- data.frame( id=rep(1:3,3), x=rnorm(9), y=rnorm(9))
> > >
> > > Question 1: how do I work with the output of "by"? for example,
> > >
> > > > b <- by( d, d$id, function(x) coef(lm( y ~ x, data=x ) ))
> > > > b
> > >
> > > d$id: 1
> > > (Intercept) x
> > > 0.2303 0.3618
> > > --------------------------------------------------------------
> > > -------------------------------------
> > > d$id: 2
> > > (Intercept) x
> > > 0.05785 -0.40617
> > > --------------------------------------------------------------
> > > -------------------------------------
> > > d$id: 3
> > > (Intercept) x
> > > 0.269 -0.378
> > >
> > > getting the categories is easy:
> > >
> > > > names(b)
> > > [1] "1" "2" "3"
> > >
> > > but how do I transform the non-name info in this by() data structure
> > > into a matrix with dimensions 3 by 2? (presumably, there is some
> > > vector operator that can do this kind of magic.)
> > >
> > >
> > > Question 2: Let's say I want to add only one of the two coefficients
> > > to d. The naive approach
> > > a <- ave( d, d$id, FUN=function(x) coef(lm( y ~ x, data=x ))[2] )
> > > gives me the right coefficient in each row, but overwrites every
> > > entry. I guess I can keep only the first column of a, and add it to
> > > d, but this seems a rather ugly and inefficient way. How is this done
> > > better?
> > >
> > > Question 3: repeat question 2, but keep both the intercept
> > > and the slope.
> > >
> > >
> > > thanks in advance, as always, for any advice.
> > >
> > > /iaw
> > > ----
> > > Ivo Welch (ivo.welch at gmail.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.
> > >
> >
>
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>
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