cheddar (version 0.1-639)

LumpNodes: Lump nodes

Description

A function that lumps together nodes in a Community.

Usage

LumpNodes(community, 
          lump, 
          title = NULL, 
          weight.by = 'N')

Value

A new object of class Community.

Arguments

community

an object of class Community

lump

a vector of of length NumberOfNodes containing names of lumped nodes. Nodes with the same value of lump will be merged.

title

the title of the new Community.

weight.by

the name of a column by which to compute weighted mean of numeric values.

Author

Lawrence Hudson

Details

If weight.by is not NULL and it is the name of a node property, it is used to compute weighted means of all the other numeric node properties. The arithmetic mean of weight.by is computed. If weight.by is NULL or is not the name of a node property, the arithmetic mean is computed for each numeric node property. Node properties that are characters or logicals are aggregated by joining unique values with a `,'. Empty character strings are ignored.

See Also

LumpTrophicSpecies, IsIsolatedNode, IsolatedNodes, NPS, weighted.mean

Examples

data(TL84)

# Lump together isolated nodes in TL84
length(which(IsIsolatedNode(TL84)))  # 6 isolated species
IsolatedNodes(TL84)                  # Names of isolated nodes

lump <- NP(TL84, 'node')             # Existing node names

# Give isolated nodes the same lump value
lump[IsolatedNodes(TL84)] <- 'Isolated nodes lumped together'
TL84.lumped <- LumpNodes(TL84, lump)

NumberOfNodes(TL84)         # 56 nodes in unlumped web
NumberOfNodes(TL84.lumped)  # 51 nodes in lumped web

IsolatedNodes(TL84.lumped)  # A single node


# This trivial example shows that no nodes are lumped if values in lump are 
# unique to each node
lump <- NP(TL84, 'node')
identical(TL84, LumpNodes(TL84, lump, title=CP(TL84, 'title')))


# Ythan Estuary contains two species that are split in to adult and 
# juvenile forms. The example below lumps these in to single species.
data(YthanEstuary)

# The names of nodes in YthanEstuary
lump <- NP(YthanEstuary, 'node')

# European flounder:
# "Platichthys flesus" and "Platichthys flesus (juvenile)"
# Lump these in to one node
lump["Platichthys flesus (juvenile)"==lump] <- "Platichthys flesus"

# Common eider:
# "Somateria mollissima" and "Somateria mollissima (juvenile)"
# Lump these in to one node
lump["Somateria mollissima (juvenile)"==lump] <- "Somateria mollissima"
YthanEstuary.lumped <- LumpNodes(YthanEstuary, lump)


# Examine the computed means for Somateria mollissima
# Arithmetic mean of N is 2592
NP(YthanEstuary.lumped, 'N')['Somateria mollissima']
mean(NP(YthanEstuary, 'N')[c("Somateria mollissima (juvenile)", 
                             "Somateria mollissima")])

# N-weighted mean of M is 1637.018
NP(YthanEstuary.lumped, 'M')['Somateria mollissima']
weighted.mean(NP(YthanEstuary, 'M')[c("Somateria mollissima (juvenile)", 
                                    "Somateria mollissima")], 
              NP(YthanEstuary, 'N')[c("Somateria mollissima (juvenile)", 
                                    "Somateria mollissima")], )


# Plot the original community and the community with lumped nodes
par(mfrow=c(1,2))
plot(YthanEstuary, highlight.nodes=c("Platichthys flesus", 
                                     "Platichthys flesus (juvenile)", 
                                     "Somateria mollissima", 
                                     "Somateria mollissima (juvenile)"))
plot(YthanEstuary.lumped, highlight.nodes=c("Platichthys flesus", 
                                            "Somateria mollissima"))