calc_t | R Documentation |
Calculate the canonical statistic 't' for a realization of a Potts Model
calc_t_full(x,ncolor) calc_t_innergrid(x, ncolor, grid, i, j) calc_t(x, ncolor, grid=NULL, i=NULL, j=NULL)
x |
2 dimensional matrix, elements in 1, ..., |
ncolor |
numeric. Number of colors in this Potts Model. |
grid |
numeric. 2 dimensional matrix, elements in 1, ...,
|
i |
numeric. Row to place the grid. |
j |
numeric. Column to place the grid. |
For a description of notation and terminology, see
composite.ll
.
Calculates the canonical statistics for a realized Potts Model.
calc_t
calls calc_t_full
if grid
is NULL
and calc_t_innergrid
otherwise.
calc_t_full
calculates the canonical statistics for the full image.
calc_t_innergrid
calculates the canonical statistics for the a
window of the image, but with that window replaced by grid
,
with the upper left corner of grid
located at x[i,j]
.
For a description of notation and terminology, see
composite.ll
.
All functions return a vector of length ncolor+1
. Elements
1,...,ncolor
contain the number of pixels of each color.
Element ncolor+1
contains the number of matching neighbor pairs
for the image.
calc_t_full
returns the values for the whole image.
calc_t_innergrid
returns the value for just the selected
window, but this includes the number of matching pairs from the
replaced window to it's neighbors. E.g. if X
is the full
image, and A(a) is the value of some window in the image
and we want to know the value of \code{t( y union X \ A(a))} this would be calc_t_full(X,
ncolor) + calc_t_innergrid(X, ncolor, y, i, j) - calc_t_innergrid(X,
ncolor, A(a), i, j)
generate_t_cache
, composite.ll
.
ncolor <- 4 beta <- log(1+sqrt(ncolor)) theta <- c(rep(0,ncolor), beta) nrow <- 32 ncol <- 32 x <- matrix(sample(ncolor, nrow*ncol, replace=TRUE), nrow=nrow, ncol=ncol) foo <- packPotts(x, ncolor) out <- potts(foo, theta, nbatch=10) x <- unpackPotts(out$final) t_stat <- calc_t(x, ncolor) t_stat_inner <- calc_t(x, ncolor, matrix(1, nrow=2, ncol=2), 1, 1)
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