Calculate the distribution of the Potts model using a brute force algorithm.

Warning: this algorithm is O\((k^n)\) and therefore will not scale for \(k^n > 2^{31} - 1\)

exactPotts(neighbors, blocks, k, beta)

Arguments

neighbors	A matrix of all neighbours in the lattice, one row per pixel.
blocks	A list of pixel indices, dividing the lattice into independent blocks.
k	The number of unique labels.
beta	The inverse temperature parameter of the Potts model.

Value

A list containing the following elements:

expectation

The exact mean of the sufficient statistic.

variance

The exact variance of the sufficient statistic.

exp_PL

Pseudo-likelihood (PL) approximation of the expectation of S(z).

var_PL

PL approx. of the variance of the sufficient statistic.