NetworkFootprint {RNetica} | R Documentation |
When a link is detached through setting a NodeParents()
to NULL
, or through copying a node but not its parent to a new
network, this leaves a stub node, an unsatisfied connection.
This function runs through the set of nodes in a network and lists the
names of all unsatisfied connections.
NetworkFootprint(net)
net |
An active |
Stub nodes – unsatisfied links or connections – can happen in two
ways. Either by setting one of the values of
NodeParents(node)
to NULL
, or by copying a node
(using CopyNodes()
) without copying its parents. (This
can also be done in the Netica GUI by detaching the link from the
parent end). This this case Netica names the
NodeInputNames()
according to the name of the old node.
The function NetworkFootprint(net)
search all of the nodes in
net
to find stub nodes, and reports the
NodeInputNames()
of the stub nodes. This function provides a
test for unsatisfied connections, and should be of assistance when
joining two networks together. The function
AdjoinNetwork(sm,em)
joins two networks together and
attempts to resolve the unsatisfied connections in em
.
One particular application of the footprint is in the EM–SM algorithm
(Almond et al, 1999; Almond and Mislevy, 1999). Here it is assumed
that nodes in the footprint of an evidence model will be joined.
Making a clique node MakeCliqueNode()
ensures that joint
information from the evidence model will find a good home in the
system model network.
A character vector giving the input names of the stub nodes in
net
. Duplicate values are removed.
Russell Almond
Almond, R. G. & Mislevy, R. J. (1999) Graphical models and computerized adaptive testing. Applied Psychological Measurement, 23, 223-238.
Almond, R., Herskovits, E., Mislevy, R. J., & Steinberg, L. S. (1999). Transfer of information between system and evidence models. In Artificial Intelligence and Statistics 99, Proceedings (pp. 181–186). Morgan-Kaufman
NeticaNode
, NodeParents()
,
MakeCliqueNode()
, NodeInputNames()
,
CopyNodes()
,AdjoinNetwork()
sess <- NeticaSession() startSession(sess) ## System/Student model EMSMSystem <- ReadNetworks(file.path(library(help="RNetica")$path, "sampleNets","System.dne"), session=sess) CompileNetwork(EMSMSystem) JunctionTreeReport(EMSMSystem) ## Evidence model for Task 1a EMTask1a <- ReadNetworks(file.path(library(help="RNetica")$path, "sampleNets","EMTask1a.dne"), session=sess) NetworkFootprint(EMTask1a) ## The corresponding clique is not in system model, so force it in. MakeCliqueNode(NetworkFindNode(EMSMSystem, NetworkFootprint(EMTask1a))) CompileNetwork(EMSMSystem) JunctionTreeReport(EMSMSystem) ## Evidence model for Task 2a EMTask2a <- ReadNetworks(file.path(library(help="RNetica")$path, "sampleNets","EMTask2a.dne"), session=sess) NetworkFootprint(EMTask2a) ## This is already a clique, so nothing to do. DeleteNetwork(list(EMSMSystem,EMTask1a,EMTask2a)) stopSession(sess)