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ergm (version 3.6.1)

ergm.formula.utils: Internal Functions for Querying, Validating and Extracting from ERGM Formulas

Description

These are all functions that are generally not called directly by users, but may be employed by other depending packages.

Usage

ergm.getmodel(formula, nw, response = NULL, silent = FALSE, role = "static", ...)


ergm.getnetwork(form, loopswarning = TRUE)


ergm.getterms(formula)


offset.info.formula(object, response = NULL) 


remove.offset.formula(object, response = NULL)


# Deprecated. Use nonsimp.update.formula() from statnet.common package.
ergm.update.formula(object, new, ..., from.new = FALSE)

Arguments

formula
a formula of the form network ~ model.term(s)
nw
the network of interest
response
charcter, name of edge attribute containing edge weights
silent
logical, whether to print the warning messages from the initialization of each model term; default=FALSE
role
A hint about how the model will be used. Used primarily for dynamic network models.
...
additional parameters for model formulation
form
same as formula, a formula of the form 'network ~ model.term(s)'
loopswarning
whether warnings about loops should be printed (T or F);default=TRUE
object
formula object to be updated
new
new formula to be used in updating
from.new
logical or character vector of variable names. controls how environment of formula gets updated.

Value

ergm.getmodel returns a 'model.ergm' object as a list containing:
  • formula : the formula inputted to ergm.getmodel
  • coef.names : a vector of coefficient names
  • offset : a logical vector of whether each term was "offset", i.e. fixed
  • terms : a list of terms and 'term components' initialized by the appropriate InitErgmTerm.X function.
  • network.stats0: NULL always??
  • etamap : the theta -> eta mapping as a list returned from
  • class : the character string "model.ergm"
ergm.getnetwork returns:
  • the network from the formula IF (i) the formula was correctly structured and (ii) the network is found within the formula's enviornment
ergm.getterms returns:
  • the terms object associated with the formula and returned by the native R function terms>. see terms.object for details about the components
terms.list.formula returns a list of formula terms, each of witch having an additional attribute "sign".ergm.update.formula, remove.offset.formula and

Details

  • The ergm.getmodel function parses the given formula, and initiliazes each ergm term via the InitErgmTerm functions to create a model.ergm object for the given network
  • The ergm.getnetwork function ensures that the network in a given formula is valid; if so, the network is returned; if not, execution is halted with warnings
  • The ergm.getterms function returns the terms of a given formula and ensures that the formula is indeed a formula with the necessary ~ operator
  • ergm.update.formula (DEPRECATED: use nonsimp.update.formula instead) is a reimplementation of update.formula that does not simplify. Note that the resulting formula's environment is set as follows. If from.new==FALSE, it is set to that of object. Otherwise, a new sub-environment of object, containing, in addition, variables in new listed in from.new (if a character vector) or all of new (if TRUE).
  • offset.info.formula returns the offset vectors associated with a formula.
  • remove.offset.formula deletes all offset terms in an ERGM formula.