define subset argument for function lm as variable?

Hi Rainer,

You could try:

subs <- expression(dead==FALSE & recTreat==FALSE)

lme(formula, subset = eval(subs))

Not tested, but something along those lines should work.

Josh

On Tue, Aug 21, 2012 at 7:44 AM, Rainer M Krug <r.m.krug at gmail.com> wrote:

Hi

I want to do a series of linear models, and would like to define the input
arguments for lm() as variables. I managed easily to define the formula
arguments in a variable, but I also would like to have the "subset" in a
variable. My reasoning is, that I have the subset in the results object.

So I wiould like to add a line like:

subs <- dead==FALSE & recTreat==FALSE

which obviously does not work as the expression is evaluated immediately. Is
is it possible to do what I want to do here, or do I have to go back to use

dat <- subset(dat, dead==FALSE & recTreat==FALSE)

?



dat <- loadSPECIES(SPECIES)
feff <- height~pHarv*year               # fixed effect in the model
reff <- ~year|plant                     # random effect in the model, where
year is the
dat.lme <- lme(
             fixed = feff,                           # fixed effect in the
model
             data  = dat,
             random = reff,                          # random effect in the
model
             correlation = corAR1(form=~year|plant), #
             subset = dead==FALSE & recTreat==FALSE, #
             na.action = na.omit
             )
dat.lm <- lm(
            formula =  feff,              # fixed effect in the model
            data = dat,
            subset = dead==FALSE & recTreat==FALSE,
            na.action = na.omit
            )

Thanks,

Rainer

--
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

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