fit_ssm: Fit a Continuous-time Random Walk state-space filter to Argos...

In ianjonsen/ctrw: a Continuous-Time Random Walk state-space model to filter Argos Least Squares or Kalman Filter location data

Description

fits a simple random walk in continuous time to filter Argos KF or LS data and predict locations on a regular time step

Usage

fit_ssm(d, span = 0.1, min.dt = 0, min.dist = 100, pf = FALSE,
  ptime, ...)

Arguments

d	a data frame of observations including Argos KF error ellipse info
span	degree of loess smoothing (range: 0 - 1) to identify potential outliers in prefilter
min.dt	minimum allowable time difference between observations; dt <= min.dt will be ignored by the SSM
min.dist	minimum distance from track to define potential outlier locations in prefilter ##' @param ptime the regular time interval, in hours, to predict to. Alternatively, a vector of prediction times, possibly not regular, must be specified as a data.frame with id and POSIXt dates.
pf	just pre-filter the data, do not fit the ctrw (default is FALSE)
...	arguments passed to sfilter, described below:
fit.to.subset	fit the SSM to the data subset determined by prefilter (default is TRUE)
psi	estimate scaling parameter for the KF measurement error model error ellipses (0 = no psi, default; 1 = single psi for semi-minor axis)
optim	numerical optimizer (nlminb or optim)
verbose	report progress during minimization

Value

a list with components

call	the matched call
predicted	a data.frame of predicted location states
fitted	a data.frame of fitted locations
par	model parameter summmary
data	the input data.frame
subset	the inpu subset vector
mem	the measurement error model used
opt	the object returned by the optimizer
tmb	the TMB object
rep	TMB sdreport
aic	the calculated Akaike Information Criterion
time	the processing time for sfilter

Examples

## Not run: 
require(dplyr)
data(ellie)
## fit KF measurement error model
fkf <- fit_ssm(ellie, min.dist = 150, ptime = 12, psi = 0)

## fit KFp measurement error model
fkfp <- fit_ssm(ellie, min.dist = 150, ptime = 12, psi = 1)

## fit LS measurement error model
fls <- fit_ssm(ellie[, 1:5], min.dist = 150, ptime = 12)

## End(Not run)

ianjonsen/ctrw documentation built on July 7, 2019, 7:30 p.m.