The error message actually is
Error in inherits(object, "formula") : object 'frmlc' not found
and it is the omitted-by-you part after the colon that matters: the
body of model.tables does not have 'frmlc' in its scope.
Here is one approach to using dynamic formulae that works in a lot of
similar situations:
test <- function(dat) {
frmlc <- as.formula("yield ~ block + Error(N/block)")
aovfit <- eval(substitute(aov(form, dat),list(form=frmlc)))
model.tables(aovfit, "means")
}
written without the pointless empty statements after the semicolons.
On Fri, 23 Jul 2010, Hannes wrote:
Hello,
I noticed that model.tables fails when applied to an aov() fit if called
inside a function. The problem seems to occur when as.formula is used inside
a function on a string containing
"<formula> + Error( x / y )"
The reason I tried to use as.formula is to generate dynamic calls to aov().
Here is a minimal example illustrating the problem:
## Example
test <- function(dat) {
frmlb <- "yield ~ block"; # WORKS
aovfit <- aov(as.formula(frmlb), dat);
print(model.tables(aovfit, "means"));
frmlc <- "yield ~ block + Error(N/block)"; # DOES NOT WORK
aovfit <- aov(as.formula(frmlc), dat);
print(model.tables(aovfit, "means"));
}
utils::data(npk, package="MASS");
frmla <- "yield ~ block + Error(N/block)"; # WORKS
aovfit <- aov(as.formula(frmla), npk);
print(model.tables(aovfit, "means"));
test(npk);
## End of example
Output of sessionInfo():
R version 2.11.1 (2010-05-31)
i386-pc-mingw32
locale:
[1] LC_COLLATE=Finnish_Finland.1252 LC_CTYPE=Finnish_Finland.1252
[3] LC_MONETARY=Finnish_Finland.1252 LC_NUMERIC=C
[5] LC_TIME=Finnish_Finland.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] tools_2.11.1
br Hannes G.
______________________________________________
R-help@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.
--
Brian D. Ripley, rip...@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
______________________________________________
R-help@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.
