Conditional probabilities in a pixel position

Computes the vector of conditional probabilities for a pixel position given a field, an interaction structure and a parameter array.

cp_mrf2d(Z, mrfi, theta, pos)

Arguments

Z

A matrix with integers in {0,...,C}.

mrfi

A mrfi object representing the interaction structure.

theta

A 3-dimensional array describing potentials. Slices represent interacting positions, rows represent pixel values and columns represent neighbor values. As an example: theta[1,3,2] has the potential for the pair of values 0,2 observed in the second relative position of mrfi.

pos

Length-2 vector with the position to compute conditional probabilities in.

Value

A numeric vector with the conditional probabilities.

See also

A paper with detailed description of the package can be found at doi: 10.18637/jss.v101.i08 .

Author

Victor Freguglia

Examples

cp_mrf2d(Z_potts, mrfi(1), theta_potts, c(57,31))
#>          0          1          2 
#> 0.46831053 0.06337894 0.46831053 
cp_mrf2d(Z_potts, mrfi(1), theta_potts*0.1, c(57,31))
#>         0         1         2 
#> 0.3547696 0.2904608 0.3547696