Node connectivity {cheddar}

Node connectivity

Description

Functions that report the connectivity of nodes in a food web.

Usage

IsBasalNode(community)
IsTopLevelNode(community) 
IsIntermediateNode(community) 
IsIsolatedNode(community) 
IsConnectedNode(community) 
IsNonBasalNode(community) 
IsNonTopLevelNode(community) 

BasalNodes(community)
TopLevelNodes(community) 
IntermediateNodes(community) 
IsolatedNodes(community) 
ConnectedNodes(community)
NonTopLevelNodes(community) 
NonBasalNodes(community)

FractionBasalNodes(community)
FractionIntermediateNodes(community)
FractionTopLevelNodes(community)
FractionIsolatedNodes(community)
FractionNonBasalNodes(community)
FractionConnectedNodes(community)
FractionNonTopLevelNodes(community)

Arguments

community

an object of class Community.

Details

Each node in a community is defined as:

isolated	No resources or consumers, other than possibly itself
basal	No resources and one or more consumers
top-level	One or more resources and no consumers, other than possibly itself
intermediate	Nodes not fitting any of the above categories

These definitions allow the following additional definitions:

connected	basal, intermediate or top-level
non-basal	isolated, intermediate or top-level
non-top-level	isolated, basal or intermediate

For each of the above seven definitions, ‘X’, there are three functions: IsX, X and FractionX. The first returns a vector of logical of length NumberOfNodes; values are TRUE for nodes that fit the definition of ‘X’. The second returns the names of nodes for which IsX returns TRUE. The third returns the proportion of nodes in the community that fit the definition of ‘X’.

Value

Either a logical vector of length NumberOfNodes or a vector of names.

Author(s)

Lawrence Hudson

See Also

NumberOfNodes, Cannibals, IsCannibal, NumberOfTrophicLinks, PredationMatrix, Degree, InDegree, OutDegree, ResourcesByNode, ConsumersByNode, ResourcesOfNodes, ConsumersOfNodes

Examples

data(TL84)

# Assemble a table of node connectivity. Only one of each of the following 
# four properties is TRUE for each node.
connectivity <- NPS(TL84, c('IsBasalNode', 'IsIsolatedNode', 
                            'IsIntermediateNode', 'IsTopLevelNode'))
connectivity

# Each row sums to 1, confirming that exactly one of the columns in each row 
# is TRUE.
all(1==rowSums(connectivity))

# These summations are 1
sum(FractionBasalNodes(TL84), 
    FractionIntermediateNodes(TL84), 
    FractionTopLevelNodes(TL84), 
    FractionIsolatedNodes(TL84))

sum(FractionConnectedNodes(TL84), 
    FractionIsolatedNodes(TL84))

sum(FractionBasalNodes(TL84), 
    FractionNonBasalNodes(TL84))

sum(FractionTopLevelNodes(TL84), 
    FractionNonTopLevelNodes(TL84))