Package edu.cmu.tetrad.sem

Class TemplateExpander

java.lang.Object

edu.cmu.tetrad.sem.TemplateExpander

public class TemplateExpander
extends Object

Expands templates for the generalized SEM PM. The template provided needs to be parseable, but the expanded template may not be parseable. If it is not, the original template was ill-formedm, and the expansion should be disgarded.

Version:

$Id: $Id

Author:

josephramsey

Method Summary

Modifier and Type	Method	Description
String	expandTemplate(String template, GeneralizedSemPm semPm, Node node)	Returns the expanded template, which needs to be checked to make sure it can be used.
static TemplateExpander	getInstance()	getInstance.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

getInstance

public static TemplateExpander getInstance()

getInstance.

Returns:

a TemplateExpander object

expandTemplate

public String expandTemplate(String template,
 GeneralizedSemPm semPm,
 Node node)
                      throws ParseException

Returns the expanded template, which needs to be checked to make sure it can be used. Try setting it as the expression for the node or freeParameters you wish to use it for.

Parameters:

template - A template formula, which includes the functions TSUM and TPROD, which are not nestable, and NEW. TSUM(f($)) = f(X1) + f(X2) + .... TPROD(f($)) = f(X1) * f(X2) * .... NEW(a) = a new parameter with name beginning with a, such as a3, if a1 and a2 have already been used.

semPm - The generalized SEM PM for which this is intended. This is needed in order to figure out what the parents of node are, and in order to determine new freeParameters. May be null. If it is null, then the template may not contain any TSUM, TPROD, or NEW expressions.

node - The node this is intended for, if there is one. Like I said, the parents of a node need to be calculated. This may be null. If it is null, the template may not contain any TSUM or TPROD expressions --i.e. any TSUM or TPROD expressions--but it may contain NEW expressions. If semPm is null, then node must be null as well, since the node is relative to a generalized SEM PM.

Returns:

The expanded template.

Throws:

ParseException - for any of a variety of reasons. It may be that the original template cannot be parsed. It may be that the expanded formula without the error term added cannot be parsed. It may be that the expanded formula contains a "$", which means there was a "$" that was not properly embedded in a TSUM or TPROD. It may be that a TSUM or TPROD was embedded inside another TSUM or TPROD.