create.grid {surveillance} | R Documentation |
Computes a matrix of initial values
Description
For a given model and a list of parameters specified as param = c(lower,upper,length)
,
create.grid
creates a grid of initial values for algo.hhh.grid
.
The resulting matrix contains all combinations of the supplied parameters
which each are a sequence of length length
from lower
to
upper
.
Note that the autoregressive parameters λ, phi and the
overdispersion parameter psi must be positive.
Only one sequence of initial values is considered for the autregressive,
endemic and overdispersion parameters to create the grid,
e.g. initial values are the same
for each one of the seasonal and trend parameters.
Usage
create.grid(disProgObj, control, params = list(epidemic = c(0.1, 0.9, 5),
endemic=c(-0.5,0.5,3), negbin = c(0.3, 12, 10)))
Arguments
disProgObj |
object of class disProg |
control |
specified model |
params |
list of parameters: param=c(lower,upper,length)
- epidemic
- autoregressive parameters λ and phi.
- endemic
- trend and seasonal parameters β,gamma_j.
- negbin
- overdispersion parameter for negative binomial model psi.
|
Value
matrix |
matrix with gridSize starting values as rows |
Author(s)
M. Paul
See Also
algo.hhh.grid
Examples
# simulate data
set.seed(123)
disProgObj <- simHHH(control = list(coefs = list(alpha =-0.5, gamma = 0.4,
delta = 0.6)),length=300)$data
# consider the model specified in a control object for algo.hhh.grid
cntrl1 <- list(lambda=TRUE, neighbours=TRUE,
linear=TRUE, nseason=1)
cntrl2 <- list(lambda=TRUE, negbin="single")
# create a grid of initial values for respective parameters
grid1 <- create.grid(disProgObj, cntrl1, params = list(epidemic=c(0.1,0.9,3),
endemic=c(-1,1,3)))
grid2 <- create.grid(disProgObj, cntrl2, params = list(epidemic=c(0.1,0.9,5),
negbin=c(0.3,12,10)))
[Package
surveillance version 1.0-3
Index]