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Save and restore mizer objects

Source: R/saveParams.R
saveParams.Rd

saveParams() saves a MizerParams object to a file. This can then be restored with readParams(). saveSim() and readSim() provide the same lifecycle for MizerSim objects.

Usage

saveParams(params, file)

readParams(file, install_extensions = FALSE)

saveSim(sim, file)

readSim(file, install_extensions = FALSE)

Arguments

params

A MizerParams object

file

The name of the file or a connection where the object is saved to or read from.

install_extensions

Logical. Should readParams() or readSim() attempt to install missing extension packages before loading them?

sim

A MizerSim object

Value

saveParams() and saveSim() return NULL invisibly. readParams() returns a MizerParams object. readSim() returns a MizerSim object.

Details

While these functions ultimately use saveRDS() and readRDS(), they do extra work to make the saved file more robust and more portable, so you should always prefer them over calling saveRDS()/readRDS() directly on a mizer object.

The complete S3 class vector is stored with the object, including any extension classes.

What saveParams() and saveSim() do beyond saveRDS()

  • They validate the object before writing it, so a corrupted or inconsistent object is caught at save time rather than when you next try to use it.

  • They check that the required extension packages are installed and stop with an informative error if they are not, so you do not save a file that you would be unable to read back.

  • They warn if the model relies on custom functions (custom rate, dynamics, selectivity or predation-kernel functions that are not provided by mizer or a registered extension package). Such functions are not stored in the file, so to share the model you also need to share an R script or R Markdown file defining them.

Before saving a model you may want to set its metadata with setMetadata().

What readParams() and readSim() do beyond readRDS()

  • They upgrade an object saved by an older version of mizer to the current structure (see upgradeParams()), so that models saved years ago still load correctly.

  • They load the extension packages that the model needs and, optionally, install any that are missing (see install_extensions), before revalidating the object.

  • readParams() reconciles the species parameters, see reconcileSpeciesParams(). A model may hold species parameter values that were written straight into the species_params slot and that mizer would therefore undo at the next recalculation. Those values are recorded as given species parameters instead, so that they survive.

See also

The guide to using mizer extension packages

Examples

# Save params to a temporary file and read them back
tmp <- tempfile(fileext = ".rds")
saveParams(NS_params, file = tmp)
#> ℹ No `a` column so using a = 0.01 in w = a l^b, with w in g and l in cm.
#> ℹ No `b` column so using the isometric default b = 3 in w = a l^b.
params <- readParams(tmp)
identical(params, NS_params)
#> [1] FALSE

# Save and read back a simulation
tmp2 <- tempfile(fileext = ".rds")
saveSim(NS_sim, file = tmp2)
sim <- readSim(tmp2)
identical(sim, NS_sim)
#> [1] TRUE