loglm
into one for
terms
.
loglm
allows dimension numbers to be used
in place of names in the formula.
denumerate
modifies such a formula into
one that
terms
can process.
denumerate(x)
loglm
, that is, it may allow dimension
numbers to stand in for names when specifying a log-linear model.
n
, have been used
to specify fixed margins these are replaced by names of the form
.vn
which may be processed by
terms
.
The model fitting function
loglm
fits
log-linear models to frequency data using iterative proportional
scaling. To specify the model the user must nominate the margins in
the data that remain fixed under the log-linear model. It is
convenient to allow the user to use dimension numbers, 1, 2, 3,
... for the first, second, third, ..., margins in a similar way to
variable names. As the model formula has to be parsed by
terms
, which treats
1
in a special way and requires parsable
variable names, these formulae have to be modified by giving genuine
names for these margin, or dimension numbers.
denumerate
replaces these numbers with
names of a special form, namely
n
is
replaced by
.vn
. This allows
terms
to parse the formula in the usual
way.
denumerate(~(1+2+3)^3 + a/b)