deal (version 1.2-4)

node: Representation of nodes

Description

An important part of a network is the list of nodes. The nodes summarize the local properties of a node, given the parents of the node.

Usage

node (idx,parents,type="discrete",name=paste(idx),
                 levels=2,levelnames=paste(1:levels),position=c(0,0)) 
## S3 method for class 'node':
print (x,filename=NA,condposterior=TRUE,condprior=TRUE,...) 
## S3 method for class 'node':
plot (x,cexscale=10,notext=FALSE,...)
prob.node (x,nw,df)
nodes(nw)
"nodes<-"(nw,value)

Arguments

x

an object of class node.

parents

a numeric vector with indices of the parents of the node.

idx

an integer, which gives the index of the node (the column number of the corresponding data frame).

type

a string, which gives the type of the node. Either "discrete" (for factors) or "continuous" (for numeric).

name

a string, which gives the name used when plotting and printing. Defaults to the column name in the data frame.

levels

an integer. If type is "discrete", this is the number of levels for the discrete variable.

levelnames

if type is "discrete", this is a vector of strings (same length as levels) with the names of the levels. If type is "continuous", the argument is ignored.

position

a numeric vector with coordinates where the node should appear in the plot. Usually set by network and drawnetwork.

df

a data frame, where the columns define the variables. A continuous variable should have type numeric and discrete varibles should have type factor.

nw

an object of class network.

value

a list of elements of class node.

filename

a string or NA. If not NA, output is printed to a file.

condprior

a logical. If TRUE, the conditional prior is printed, see conditional.

condposterior

a logical. If TRUE, the conditional posterior is printed, see learn.

cexscale

a numeric. Scale parameter to set the size of the nodes.

notext

a logical. If TRUE, no text is displayed in the nodes on the plot.

...

additional plot arguments.

Value

• An object of class node, which is a list with the following elements (properties),
• idx
  an integer. A unique index for this node. It MUST correspond to the column index of the variable in the data frame.
• name
  a string. The printed name of the node.
• type
  a string. Either "continuous" or "discrete".
• levels
  an integer. If the node is of type "discrete", this integer is the number of levels of the node.
• levelnames
  if type is "discrete", this is a vector of strings (same length as levels) with the names of the levels. If type is "continuous", the node does not have this property.
• parents
  a vector of indices of the parents to this node. It is best to manage this vector using the insert function.
• prob
  a numeric vector, matrix or multiway array, giving the initial probability distribution. If the node is discrete, prob is a multiway array. If the node is continuous, prob is a matrix with one row for each configuration of the discrete parents, reducing to a vector if the node has no discrete parents.
• condprior
  a list, generated by conditional giving the parameter priors deduced from jointprior using the master prior procedure (see localmaster).
• condposterior
  a list, which gives the parameter posteriors obtained from learnnode.
• loglik
  a numeric giving the log likelihood contribution for this node, calculated in learnnode.
• simprob
  a numeric vector, matrix or multiway array similar to prob, added by makesimprob and used by simulation.

Details

The operations on a node are typically done when operating on a network, so these functions are not to be called directly. When a network is created with network, the nodes in the nodelist are created using the node procedure. Local probability distributions are added as the property prob to each node using prob.node. If the node is continuous, this is a numeric vector with the conditional variance and the conditional regression coefficients arising from a regression on the continuous parents, using data. If the node has discrete parents, prob is a matrix with a row for each configuration of the discrete parents. If the node is discrete, prob is a multiway array which gives the conditional probability distribution for each configuration of the discrete parents. The generated prob can be replaced to match the prior information available. nodes gives the list of nodes of a network.

References

Further information about deal can be found at: http://www.math.auc.dk/novo/deal.