| denumerate {MASS} | R Documentation |
Transform an Allowable Formula for 'loglm' into one for 'terms'
Description
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.
Usage
denumerate(x)
Arguments
x |
A formula conforming to the conventions of |
Details
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 parseable 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.
Value
A linear model formula like that presented, except that where
dimension numbers, say n, have been used to specify fixed
margins these are replaced by names of the form .vn which may
be processed by terms.
See Also
Examples
denumerate(~(1+2+3)^3 + a/b)
## which gives ~ (.v1 + .v2 + .v3)^3 + a/b