Changes in Version 1.1-2
o Added a str() method.
Changes in Version 1.1-1
o The CITATION was incorrect and is fixed now.
Changes in Version 1.1-0
o All methods returning "formula" or "Formula" objects now preserve the
environment of the originally supplied object by default.
o The default and formula methods of as.Formula() methods now also take
an env argument.
Changes in Version 1.0-1
o Added a terms = FALSE argument to model.part() method for "Formula"
objects. This can be leveraged when processing multiple offsets.
For example for y ~ x + offset(o1) | z + offset(o2). See ?model.part
for a worked example.
Changes in Version 1.0-0
o package now published in Journal of Statistical Software,
see http://www.jstatsoft.org/v34/i01/
and citation("Formula") within R.
o added an all.equal() method for "Formula" objects that produces
more intelligible output in case the result is not TRUE.
o fixed an error of the update() method for "Formula" objects
without LHS.
Changes in Version 0.2-0
o Major revision (not fully backward compatible) to enable support
for multiple responses and multiple parts on the right-hand side
such as
y1 | y2 ~ x
y1 + y2 ~ x1 + x2 | z1
y ~ u1 + u2 | v1 | x1 + x2
and combinations of these.
o Formula objects now consist of the original formula plus two
attributes "lhs" and "rhs" that contain the parts of the decomposed
left- and right-hand side, respectively.
o Most methods take arguments "lhs" and "rhs" which allow selection
of the desired parts on the left- and right-hand side respectively,
e.g., in a model.frame() or model.matrix().
o The previous arguments response = TRUE/FALSE and
part = "first"/"second"/"both" were not flexible enough anymore
and have been deprecated. Use the streamlined lhs/rhs arguments
instead.
o vignette("Formula", package = "Formula") illustrates usage of
the tools provided by the package and explains the ideas underlying
its implementation.
Changes in Version 0.1-3
o added CITATION file.
o added a has.intercept function with methods for formula and
Formula objects.
o change the default value for model.frame.Formula: "both" for a
two-part formula and "first" otherwise.
Changes in Version 0.1-2
o Bug fix: as.Formula() failed for very long formulas.
Changes in Version 0.1-1
o First CRAN release of package "Formula" for extended
formula processing. This package is still under development
and the interface might change in future versions.
o Currently, this enables processing of formulas such as
y ~ x1 + x2 | z1 + z2 + z3
with two parts on the right hand side.
o Generalization to further formulas are planned (i.e.,
not implemented yet), e.g.,
y1 + y2 ~ x1 + x2 + x3
y ~ x1 + x2 | u1 | v1 + v2 + v3 | ...
i.e., multiple responses and multi-part formulas.