jitter: Iteratively run Stock Synthesis with jittered starting values

In r4ss/r4ss: R Code for Stock Synthesis

Iteratively run Stock Synthesis with jittered starting values

Description

Iteratively run a Stock Synthesis model with different jittered starting parameter values based on the jitter fraction. Output files are renamed in the format Report1.sso, Report2.sso, etc.

Usage

jitter(
  dir = NULL,
  mydir = lifecycle::deprecated(),
  Intern = lifecycle::deprecated(),
  Njitter,
  printlikes = TRUE,
  jitter_fraction = NULL,
  init_values_src = NULL,
  exe = "ss3",
  verbose = FALSE,
  extras = NULL,
  ...
)

Arguments

dir	Directory where model files are located.
mydir	Deprecated. Use dir instead.
Intern	Deprecated. Use show_in_console instead.
Njitter	Number of jitters, or a vector of jitter iterations. If length(Njitter) > 1 only the iterations specified will be run, else 1:Njitter will be executed.
printlikes	A logical value specifying if the likelihood values should be printed to the console.
jitter_fraction	The value, typically 0.1, used to define a uniform distribution in cumulative normal space to generate new initial parameter values. The default of NULL forces the user to specify the jitter_fraction in the starter file, and this value must be greater than zero and will not be overwritten.
init_values_src	Either zero or one, specifying if the initial values to jitter should be read from the control file or from the par file, respectively. The default is NULL, which will leave the starter file unchanged.
exe	Executable name. Can be just the name of the executable file if it is in the specified directory or in the user's PATH. Can also include the absolute path or a path relative to the specified directory. Needs to be a single character string, not a vector. On Windows, exe can optionally have the .exe extension appended; on Unix-based systems (i.e., Mac and Linux), no extension should be included.
verbose	A logical value specifying if output should be printed to the screen.
extras	Additional ADMB command line arguments passed to the executable, such as "-nohess"
...	Additional arguments passed to run(), such as show_in_console, and skipfinished.

Details

This function will loop through models using the default strategy set by the future package in the current working environment. In general, this means models will run sequentially. To run multiple models simultaneously using parallel computing, see future::plan()

Note that random number generation occurs outside of R directly in stock synthesis. When running jitters in parallel (i.e. future strategy is not sequential), no formal steps are taken to ensure independence of random numbers generated across cores. However, when running in parallel, there is a pause of i seconds before the ith jitter starts. The stock synthesis random number seed is based on the system time down to the second, so this is intended to produce random numbers from different seeds for each jitter. Random numbers may still not technically be considered statistically independent. If jitter results are only used as a general heuristic for model convergence, this mild lack of independence should not matter much.

When running models in parallel, the transfer of large files leads to expensive overheads and parallel processing may not be faster. Covariance files are especially expensive to transfer, so the option extras = '-nohess' is recommended when using parallel processing.

Value

A vector of likelihoods for each jitter iteration.

Author(s)

James T. Thorson, Kelli F. Johnson, Ian G. Taylor, Kathryn L. Doering, Kiva L. Oken, Elizabeth F. Perl

See Also

Other run functions: copy_SS_inputs(), populate_multiple_folders(), profile(), retro(), run(), tune_comps()

Examples

## Not run: 
#### Run jitter from par file with arbitrary, but common, choice of 0.1
modeldir <- tail(dir(system.file("extdata", package = "r4ss"), full.names = TRUE), 1)
numjitter <- 25
jit.likes <- jitter(
  dir = modeldir, Njitter = numjitter,
  jitter_fraction = 0.1, init_values_src = 1
)

#### Run same jitter in parallel
ncores <- parallelly::availableCores(omit = 1)
future::plan(future::multisession, workers = ncores)
jit.likes <- jitter(
  dir = modeldir, Njitter = numjitter,
  jitter_fraction = 0.1, init_values_src = 1
)
future::plan(future::sequential)

#### Read in results using other r4ss functions
# (note that un-jittered model can be read using keyvec=0:numjitter)
profilemodels <- SSgetoutput(dirvec = modeldir, keyvec = 1:numjitter, getcovar = FALSE)
# summarize output
profilesummary <- SSsummarize(profilemodels)
# Likelihoods
profilesummary[["likelihoods"]][1, ]
# Parameters
profilesummary[["pars"]]

## End(Not run)

r4ss/r4ss documentation built on March 29, 2025, 8:36 p.m.