Built-in callbacks

Callbacks inspect the state and accumulated result after each completed SMC iteration. Pass a list through callbacks when constructing a pre-built sampler or a SequentialMonteCarlo runner.

Available callbacks

The following callbacks are available from sequince.callbacks:

Callback	Purpose
TracePlot	Plot particle coordinates across the iteration history.
IntermediateParticlesPlot	Save a corner-style plot of the current particle population.
StatePlot	Plot selected metadata histories, ESS, or the normalizing constant.
AdaptiveMutationPlot	Plot completed mutation budgets, acceptance rates, and accepted moves.
MutationChainPlot	Plot stored chains from mutation step outputs.
TransformedMutationChainPlot	Plot stored mutation chains in the active transform’s coordinates.
ParticleTransformPlot	Save a corner-style plot of the current particles in transformed coordinates.

Configuring plot callbacks

For example, configure a trace plot and histories of ESS and temperature:

from sequince.callbacks import StatePlot, TracePlot

callbacks = [
    TracePlot(outdir="plots", every=5),
    StatePlot(metadata_keys=["ess", "beta"], outdir="plots", every=5),
]

Pass this list as callbacks=callbacks to the sampler constructor. outdir selects the output directory, which defaults to the current directory. every controls the interval between callback invocations; callbacks run on their first invocation and then at the requested interval.

TracePlot, StatePlot, and AdaptiveMutationPlot update their configured filename. The other plot callbacks use base_filename and append the iteration number to save separate images.

Chain plots require mutation steps configured with store_chains=True. MutationChainPlot can select a step with step_index; by default it searches all step outputs. AdaptiveMutationPlot selects the mutation output at step_index=2 by default, so adjust this for your pipeline. Transform plots require a fitted transform in context metadata, selected by metadata_key. Corner-style plots require the corner extra; see Installation for optional dependencies.

For your own reporting or run-control logic, see Custom callbacks. Checkpoint writers are configured separately; see Checkpointing.