Changes in Version 1.2-2
o Enhance Formula() so that if a "Formula" is supplied it is simply
returned unchanged (rather than throwing a warning).
o Enhance update() method for "Formula" object so that also the "new"
formula can be a "Formula" object.
Changes in Version 1.2-1
o Bug fix for formulas with transformed variables on the left-hand
side (e.g., cbind(), log(), or Surv()) and one ore more '.' on the
right-hand side. The terms() and hence the model.frame() now work
smoothly. When using model.part() the same Formula (plus 'dot'
argument) has to be supplied when preparing the model.frame() and
the model.part().
Changes in Version 1.2-0
o Extended processing of formulas with one or more '.' on the
right-hand side.
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.