stlgcppm {stopp} | R Documentation |
Fit a log-Gaussian Cox process model to a spatio-temporal point pattern
Description
This function estimates a log-Gaussian Cox process (LGCP), following the **joint minimum contrast** procedure introduced in Siino et al. (2018) .
Three covariances are available: separable exponential, Gneiting, and De Iaco-Cesare.
If the first
and second
arguments are set to local
, a local
log-Gaussian
Cox process is fitted by means of the ** locally weighted minimum contrast**
procedure proposed in
D'Angelo et al. (2023).
Usage
stlgcppm(
X,
formula = ~1,
verbose = TRUE,
seed = NULL,
cov = c("separable", "gneiting", "iaco-cesare"),
first = c("global", "local"),
second = c("global", "local"),
mult = 4,
hs = c("global", "local"),
npx0 = 10,
npt0 = 10,
itnmax = 100,
min_vals = NULL,
max_vals = NULL
)
Arguments
X |
A |
formula |
An object of class |
verbose |
Default to TRUE |
seed |
The seed used for the simulation of the dummy points. Default to
|
cov |
Covariance function to be fitted for the second-order intensity function.
Default to |
first |
Character string indicating whether to fit a first-order intensity function
with global or local parameters:
either |
second |
Character string indicating whether to fit a second-order intensity function
with global or local parameters:
either |
mult |
The multiplicand of the number of data points, for setting the number of dummy points to generate for the quadrature scheme |
hs |
Character string indicating whether to select fixed or variable bandwidths
for the kernel weights to be used in the log-likelihood.
In any of those cases, the well-supported rule-of-thumb for choosing the
bandwidth of a Gaussian kernel density estimator is employed.
If |
npx0 |
A positive integer representing the spatial distance to np-th closest event. Used in the computation of the local bandwidth. Suitable values are in the range from 10 (default) to 100. |
npt0 |
A positive integer representing the temporal distance to np-th closest event. Used in the computation of the local bandwidth. Suitable values are in the range from 10 (default) to 100. |
itnmax |
Maximum number of iterations to run in the optimization procedure for the estimation of the second-order intensity parameters. |
min_vals |
Minimum values of the optimization procedure for the minimum contrast. |
max_vals |
Maximum values of the optimization procedure for the minimum contrast. |
Details
Following the inhomogeneous specification in Diggle et al. (2013), we consider LGCPs with intensity
\Lambda(\textbf{u},t)=\lambda(\textbf{u},t)\exp(S(\textbf{u},t)).
Value
A list of the class stlgcppm
, containing
IntCoefs
The fitted coefficients of the first-order intensity function
CovCoefs
The fitted coefficients of the second-order intensity function
X
The stp object provided as input
formula
The formula provided as input
cov
A string with the chosen covariance type
l
Fitted first-order intensity
mu
Mean function of the random intensity
mod_global
The glm object of the model fitted to the quadrature scheme for the first-order intensity parameters estimation
newdata
The data used to fit the model, without the dummy points
time
Time elapsed to fit the model, in minutes
Author(s)
Nicoletta D'Angelo, Giada Adelfio, and Marianna Siino
References
Baddeley, A. (2017). Local composite likelihood for spatial point processes. Spatial Statistics, 22, 261-295.
D'Angelo, N., Adelfio, G., and Mateu, J. (2023). Locally weighted minimum contrast estimation for spatio-temporal log-Gaussian Cox processes. Computational Statistics & Data Analysis, 180, 107679.
Diggle, P. J., Moraga, P., Rowlingson, B., and Taylor, B. M. (2013). Spatial and spatio-temporal log-gaussian cox processes: extending the geostatistical paradigm. Statistical Science, 28(4):542–563.
Gabriel, E., Rowlingson, B. S., and Diggle, P. J. (2013). stpp: An R Package for Plotting, Simulating and Analyzing Spatio-Temporal Point Patterns. Journal of Statistical Software, 53(2), 1–29. https://doi.org/10.18637/jss.v053.i02
Siino, M., Adelfio, G., and Mateu, J. (2018). Joint second-order parameter estimation for spatio-temporal log-Gaussian Cox processes. Stochastic environmental research and risk assessment, 32(12), 3525-3539.
See Also
print.stlgcppm, summary.stlgcppm, localsummary, plot.stlgcppm, localplot
Examples
catsub <- stp(greececatalog$df[1:200, ])
lgcp1 <- stlgcppm(catsub)