| as.carCM {nimble} | R Documentation |
Convert weights vector to parameters of dcar_proper distributio
Description
Convert weights vector to C and M parameters of dcar_proper distribution
Usage
as.carCM(adj, weights, num)
Arguments
adj |
vector of indices of the adjacent locations (neighbors) of each spatial location. This is a sparse representation of the full adjacency matrix. |
weights |
vector of symmetric unnormalized weights associated with each pair of adjacent locations, of the same length as adj. This is a sparse representation of the full (unnormalized) weight matrix. |
num |
vector giving the number of neighbors of each spatial location, with length equal to the total number of locations. |
Details
Given a symmetric matrix of unnormalized weights, this function will calculate corresponding values for the C and M arguments suitable for use in the dcar_proper distribution. This function can be used to transition between usage of dcar_normal and dcar_proper, since dcar_normal uses the adj, weights, and num arguments, while dcar_proper requires adj, num, and also the C and M as returned by this function.
Here, C is a sparse vector representation of the row-normalized adjacency matrix, and M is a vector containing the conditional variance for each region. The resulting values of C and M are guaranteed to satisfy the symmetry constraint imposed on C and M, that M^{-1} C is symmetric, where M is a diagonal matrix and C is the row-normalized adjacency matrix.
Value
A named list with elements C and M. These may be used as the C and M arguments to the dcar_proper distribution.
Author(s)
Daniel Turek