enaR (version 2.9.1)

cycliv: Analysis of Feeding Cycles in a Network

Description

Performs the full cycle analysis on the living subset of the network based on the algorithm described in Ulanowicz (1983) and implemented in NETWRK 4.2b. It returns data.frames with details of the simple cycles and nexus, vectors of Cycle distributions and Normalized distribution and matrices of Residual Flows and Aggregated Cycles.

Usage

cycliv(x)

Arguments

x

a network object. This includes all weighted flows into and out of each node. It must also include the "Living" vector that identifies the living (TRUE/FALSE) status of each node. Also, non-living nodes must be placed at the end of the node vector. The function netOrder can be used to reorder the network for this.

Value

Table.cycle

data.frame that presents the details of the simple cycles in the network. It contains "CYCLE" the cycle number, "NEXUS" the nexus number corresponding to the cycle, "NODES" the nodes constituting the cycle

Table.nexus

data.frame that presents the different nexuses characterized by their corresponding weak arcs. It contains "NEXUS" the nexus number, "CYCLES" the number of simple cycles present in that Nexus, "W.arc.From" the starting node of the corresponding weak arc, "W.arc.To" the ending node of the corresponding weak arc and "W.arc.Flow" the flow through that weak arc

CycleDist

vector of the Cycle Distribution that gives the flow which is cycling in loops of different sizes

NormDist

vector of the Normalized Distribution i.e. the Cycle Distribution normalized by the Total System Throughput for the network

ResidualFlows

matrix of the straight-through (acyclic) flows in the network

AggregatedCycles

matrix of the Aggregated Biogeochemical Cycles in the network

ns

vector of the full cycle analysis based network statistics. These include "NCYCS" the number of simple cycles identified in the network, "NNEX" the number of the disjoint cycles or number of Nexuses detected in the network and "CI" the cycling index of the network.

References

Johnson, D.B. 1975. Finding all the elementary circuits of a directed graph. SIAM J. Comput. 4:77--84

Ulanowicz, R.E. 1983. Identifying the structure of cycling in ecosystems. Methematical Biosciences 65:219--237

Ulanowicz, R.E. and Kay, J.J. 1991. A package for the analysis of ecosystem flow networks. Environmental Software 6:131 -- 142.

See Also

enaTroAgg, enaCycle, netOrder

Examples

data(troModels)
liv.cyc <- cycliv(troModels[[6]])
attributes(liv.cyc)