NormalizeInfo function

Normalize tree distances

NormalizeInfo() is an internal function used to normalize information against a reference, such as the total information present in a pair of trees.

NormalizeInfo(
  unnormalized,
  tree1,
  tree2,
  InfoInTree,
  infoInBoth = NULL,
  how = TRUE,
  Combine = "+",
  ...
)

Arguments

• unnormalized: Numeric value, vector or matrix to be normalized.

• tree1, tree2: Trees from which unnormalized was calculated.

• InfoInTree: Function to calculate the information content of each tree.

• infoInBoth: Optional numeric specifying information content of both trees independently. If unspecified (NULL), this will be calculated using the method specified by how.

• how: Method for normalization, perhaps specified using the normalize

  argument to a tree distance function. See details for options.

• ...: Additional parameters to InfoInTree() or how().

Returns

NormalizeInfo() returns an object corresponding to the normalized values of unnormalized.

Details

The unnormalized value(s) are normalized by dividing by a denominator calculated based on the how parameter. Valid options include:

• FALSE: No normalization is performed; the unnormalized values are returned.
• TRUE: Unless infoInBoth is specified, the information in each tree is computed using InfoInTree(), and the two values combined using Combine().
• A numeric value, vector or matrix: how is used as the denominator; the returned value is unnormalized / how.
• A function: Unless infoInBoth is specified, the information in each tree is computed using InfoInTree(), and the two values combined using how. NormalizeInfo(how = Func) is thus equivalent to NormalizeInfo(how = TRUE, Combine = Func).

Examples

library("TreeTools", quietly = TRUE)
pair1 <- c(BalancedTree(9), StarTree(9))
pair2 <- c(BalancedTree(9), PectinateTree(9))

# We'll let the number of nodes define the total information in a tree
Nnode(pair1)
Nnode(pair2)

# Let's normalize a unit distance
rawDist <- cbind(c(1, 1), c(1, 1))

# With `Combine = "+"`, the maximum distance is the sum of
# the information in each tree
denominator <- outer(Nnode(pair1), Nnode(pair2), "+")

NormalizeInfo(rawDist, pair1, pair2, InfoInTree = ape::Nnode, Combine = "+")
rawDist / denominator

# A denominator can be specified manually using `how`:
NormalizeInfo(rawDist, pair1, pair2, InfoInTree = ape::Nnode, how = 16)
rawDist / 16

# `how` also allows the denominator to be computed from trees:
outer(Nnode(pair1), Nnode(pair2), pmin)
NormalizeInfo(rawDist, pair1, pair2, InfoInTree = ape::Nnode, how = pmin)
rawDist / outer(Nnode(pair1), Nnode(pair2), pmin)

Author(s)

Martin R. Smith

(martin.smith@durham.ac.uk)