The function estimates transition probabilities matrices for a \(1\)-D continuous lag spatial Markov chain.
transiogram(data, coords, direction, max.dist = Inf,
mpoints = 20, tolerance = pi / 8, reverse = FALSE)
An object of the class transiogram
is returned. The function print.transiogram
is used to print computed probabilities. The object is a list with the following components:
a 3-D array containing the probabilities.
a 3-D array containing the standard error calculated for the log odds of the transition probabilities.
a vector containing one-dimensional lags.
a character string which specifies that computed probabilities are empirical.
a categorical data vector of length \(n\).
an \(n \times d\) matrix where each row denotes the \(d\)-D coordinates of data locations.
a \(d\)-D numerical vector (or versor) which represents the chosen direction.
a numerical value which defines the maximum lag value. It's Inf
by default.
a numerical value which defines the number of lag intervals.
a numerical value for the tolerance angle (in radians). It's pi/8
by default.
a logical value. If TRUE
the transition probabilities of the reversible chain are also computed. It's FALSE
by default.
Luca Sartore drwolf85@gmail.com
Empirical probabilities are estimated by counting such pairs of observations which satisfy some properties, and by normalizing the result.
A generic pair of sample points \(s_i\) and \(s_j\), where \(i \neq j\), must satisfy the following properties:
\(\Vert s_i - s_j \Vert \in [a, a+\frac{m}{n}],\) where \(a\) is a non negative real value, while \(m\) denotes the maximum lag value (max.dist
) and \(n\) is the number of lag intervals (mpoints
).
the lag vector \(h = s_i - s_j\) must have the same direction of the vector \(\phi\) (direction
) with a certain angular tolerance
.
Carle, S. F., Fogg, G. E. (1997) Modelling Spatial Variability with One and Multidimensional Continuous-Lag Markov Chains. Mathematical Geology, 29(7), 891-918.
Sartore, L. (2010) Geostatistical models for 3-D data. M.Phil. thesis, Ca' Foscari University of Venice.
predict.tpfit
, predict.tpfit
, plot.transiogram
# \donttest{
data(ACM)
# Estimate empirical transition
# probabilities by points
transiogram(ACM$MAT3, ACM[, 1:3], c(0, 0, 1), 200, 5)
# }
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