On 09/02/15 06:46, Ravi Varadhan wrote:
Hi,
I would like to run lme() on a number of response variables in a
dataframe in an automatic manner. Bu, when I use
eval(parse(text=yname)) to denote the LHS of the formula in lme(), I
get the following error message:
require(nlme)
mod2 <- with(subset(labdata2, Transplant_type!=0 & time >0),
lme(eval(parse(text=yname)) ~ time + as.factor(gvhd), random =
~1|Patient, correlation = corAR1(), method="ML",
na.action=na.omit))
Error in model.frame.default(formula = ~Patient + yname + time +
gvhd, : variable lengths differ (found for 'yname')
The same usage works well in lme4::lmer without any problems.
It seems that there is a problem in how the formula object is
evaluated in lme(). Is there an alternative way to do this?
What about trying some'at lahk:
fmla <- as.formula(paste(yname,"~ time + as.factor(gvhd)"))
mod2 <- with(...., lme(fmla, random = ....))
Also you would probably be better off using the data argument rather
then using with(); this could have some impact on the environment in
which the formula is evaluated.
Just stabbing in the dark here since you did not provide a reproducible
example.
cheers,
Rolf Turner
--
Rolf Turner
Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276
Home phone: +64-9-480-4619
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