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ttbary (version 0.3-0)

sumppdistnet: Compute Sum of q-th Powers of Distances Between a Point Pattern and a Collection of Point Patterns on a Network

Description

Based on the shortest-path metric in a network, determine the TT-p-distances (or RTT-p-distances) between a single point pattern zeta and a collection of point patterns. Then compute the sum of \(q\)-th powers of these distances. The point patterns are specified by vectors of indices referring to the vertices in the network.

Usage

sumppdistnet(
  dmat,
  zeta,
  ppmatrix,
  penalty = 1,
  type = c("tt", "rtt", "TT", "RTT"),
  p = 1,
  q = 1
)

Value

A nonnegative number, the q-th order sum of the TT-p- or RTT-p-distances between the patterns represented by zeta and ppmatrix. This number has an attribute

distances that contains the individual distances.

Arguments

dmat

the distance matrix of a network containing all shortest-path distances between its vertices.

zeta

a vector specifying the vertex-indices of zeta.

ppmatrix

a matrix specifying in its columns the vertex-indices of the point patterns in the collection. A virtual index that is one greater than the maximum vertex-index in the network can be used to fill up columns so that they all have the same length.

penalty

a positive number. The penalty for adding/deleting points.

type

either "tt"/"TT" for the transport-transform metric or "rtt"/"RTT" for the relative transport-transform metric.

p

a number \(>0\). Matchings between zeta and the patterns in ppmatrix are chosen such that the p-th order sums (\(\ell_p\)-norms) of the shortest-path distances are minimized.

q

a number \(>0\).

Details

The main purpose of this function is to evaluate the relative performance of approximate \(q\)-th order barycenters of point patterns. A true \(q\)-th order barycenter of the point patterns \(\xi_1,\ldots,\xi_k\) with respect to the TT-p metric \(\tau_p\) minimizes $$\sum_{j=1}^k \tau_p(\xi_j, \zeta)^q$$ in \(\zeta\).

The most common choices are p = q = 1 and p = q = 2. Other choices have not been tested.

See Also

kmeansbarynet, sumppdist

Examples

Run this code
  # See examples for kmeansbarynet
  

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