Thomas Alexander Gerds <tag <at> biostat.ku.dk> writes:
>
> Dear List
>
> I am looking for the recommended way to create a formula inside a
> function with an empty environment. I tried several versions (see
> below), and one of them seemed to work, but I dont understand why there
> is a difference between .GlobalEnv and the environment inside a
> function. I would be greatful for any reference or explanation or
> advice.
[snip]
>From ?formula
Environments:
A formula object has an associated environment, and this
environment (rather than the parent environment) is used by
'model.frame' to evaluate variables that are not found in the
supplied 'data' argument.
So write four functions that:
1) creates a formula
2) creates some data
3) evaluates a formula using model.frame (even implicitly with lm(),say)
4) calls the functions from 1, 2, and 3
When you run '4', the result will depend on the environment of data from 2
and the environment of the formula from 1. If they are both in the same
environment, fine. If not, you might get lucky and have the data in a place
where it will be found nevertheless.
If you are really unlucky the '4' function will find some other data that
match the formula and use it.
HTH,
Chuck
______________________________________________
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.
