.extract.fd.formulae | R Documentation |
This function is used in tergm.EGMME.initialfit
and also when targets or monitoring
formulas are specified by characters. It makes a basic attempt to identify the
formation and dissolution formulas within a larger combined formula (which may also
include non-separable terms). Instances of Form
at the top level (which may occur
inside offset
) contribute to the formation formula; instances of Persist
and
Diss
at the top level (which may also occur inside offset
) contribute to the
dissolution formula. All other terms are regarded as non-separable; this includes instances
of Form
, Persist
, and Diss
that occur inside other operator terms,
including inside Offset
, and also includes all interactions at the top level (for which
the top level term is effectively the interaction operator *
or :
),
whether or not they include Form
, Persist
, and/or Diss
.
The formation and dissolution formulas are obtained by adding
the contributing terms, replacing Form
and Persist
with trivial operators that protect
the environments of their formula arguments but have no effect on statistics or coefficient names
(meaning the formulas effectively become cross-sectional), and replacing Diss
by a similar operator
that negates statistics. These are included in the return value as the form
and pers
elements of the list (the "dissolution" formula really being the persistence formula), which also includes
the formula of non-separable terms as nonsep
, and the formula of all terms after replacing
Form
, Persist
, and Diss
as described above as all
.
If usage proves problematic, one may specify the monitoring and/or targets formulas explicitly
(rather than by characters), and one may pass initial coefficient values for the EGMME to avoid
running tergm.EGMME.initialfit
.
.extract.fd.formulae(formula)
formula |
a |
A list
containing form
, pers
, nonsep
, and all
formulas as described above.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.