querygrain: Query a Bayesian network

In gRain: Bayesian Networks

Query a Bayesian network

Description

Query an independence network, i.e. obtain the conditional distribution of a set of variables - possibly (and typically) given finding (evidence) on other variables.

Usage

querygrain(
  object,
  nodes = nodeNames(object),
  type = "marginal",
  evidence = NULL,
  exclude = TRUE,
  normalize = TRUE,
  simplify = FALSE,
  result = "array",
  details = 0
)

Arguments

object	A grain object.
nodes	A vector of nodes; those nodes for which the (conditional) distribution is requested.
type	Valid choices are "marginal" which gives the marginal distribution for each node in nodes; "joint" which gives the joint distribution for nodes and "conditional" which gives the conditional distribution for the first variable in nodes given the other variables in nodes.
evidence	An alternative way of specifying findings (evidence), see examples below.
exclude	If TRUE then nodes on which evidence is given will be excluded from nodes (see above).
normalize	Should the results be normalized to sum to one.
simplify	Should the result be simplified (to a dataframe) if possible.
result	If "data.frame" the result is returned as a data frame (or possibly as a list of dataframes).
details	Debugging information

Value

A list of tables with potentials.

Note

setEvidence() is an improvement of setFinding() (and as such setFinding is obsolete). Users are recommended to use setEvidence() in the future.

setEvidence() allows to specification of "hard evidence" (specific values for variables) and likelihood evidence (also known as virtual evidence) for variables.

The syntax of setEvidence() may change in the future.

Author(s)

Søren Højsgaard, [e-mail]

References

Søren Højsgaard (2012). Graphical Independence Networks with the gRain Package for R. Journal of Statistical Software, 46(10), 1-26. https://www.jstatsoft.org/v46/i10/.

See Also

setEvidence, getEvidence, retractEvidence, pEvidence

Examples

testfile <- system.file("huginex", "chest_clinic.net", package = "gRain")
chest <- loadHuginNet(testfile, details=0)
qb <- querygrain(chest)
qb

lapply(qb, as.numeric) # Safe
sapply(qb, as.numeric) # Risky

gRain documentation built on Oct. 18, 2024, 1:07 a.m.