Node connectivity {cheddar} | R Documentation

## 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))

[Package cheddar version 0.1-633 Index]