Learn R Programming

ttbary (version 0.3-0)

sumppdist: Compute Sum of q-th Powers of Distances Between a Point Pattern and a List of Point Patterns

Description

Determine the Euclidean distance based TT-p-distances (or RTT-p-distances) between a single point pattern zeta and each point pattern in a list pplist. Then compute the sum of \(q\)-th powers of these distances.

Usage

sumppdist(
  zeta,
  pplist,
  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 zeta and each pattern in pplist. This number has an attribute

distances that contains the individual distances.

Arguments

zeta

an object of class ppp.

pplist

an object of class ppplist or an object that can be coerced to this class, such as a list of ppp objects.

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 pplist are chosen such that the p-th order sums (\(\ell_p\)-norms) of the Euclidean distances are minimized.

q

a number \(>0\).

Author

Dominic Schuhmacher schuhmacher@math.uni-goettingen.de

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

ppdist for computation of TT-p- and RTT-p-metrics,
kmeansbary for finding a local minimum of the above sum for p = q = 2

Examples

Run this code
  # See the examples for kmeansbary
  

Run the code above in your browser using DataLab