/// <summary>
/// Create an early stopper hook for a certain parameter that stops training if the parameter does not improve for <see cref="patience"/> time steps.
/// Improve means reach a new <see cref="ExtremaTarget.Max"/> by default or a new <see cref="ExtremaTarget.Min"/> if specified in the <see cref="target"/>.
/// </summary>
/// <param name="parameter">The parameter identifier.</param>
/// <param name="patience">The patience (number of sequential decreases of the parameter, i.e. how many times the training can let us down before we call it a day).</param>
/// <param name="target">The target for the given value (i.e. should it be a big or a small value).</param>
public EarlyStopperHook(string parameter, int patience, ExtremaTarget target = ExtremaTarget.Max) : base(new TimeStep(TimeScale.Epoch, 1))
{
string accumulatedParameter = "shared." + parameter.Replace('.', '_') + "_accumulated";
NumberAccumulatorHook accumulator = new NumberAccumulatorHook(parameter, accumulatedParameter, Utils.TimeStep.Every(1, TimeScale.Iteration));
RequireHook(accumulator);
On(new ExtremaCriteria(accumulatedParameter, target).Negate().Repeated(patience, withoutInterruption: true));
}
/// <summary>
/// Create an extrema criteria that fires when a certain parameter is at a certain extrema (min / max).
/// </summary>
/// <param name="parameter">The parameter (identifier) to check.</param>
/// <param name="target">The target extrema (min / max).</param>
public ExtremaCriteria(string parameter, ExtremaTarget target) : base(parameter)
{
if (parameter == null)
{
throw new ArgumentNullException(nameof(parameter));
}
if (!Enum.IsDefined(typeof(ExtremaTarget), target))
{
throw new InvalidEnumArgumentException(nameof(target), (int)target, typeof(ExtremaTarget));
}
ParameterRegistry["parameter_identifier"] = parameter;
ParameterRegistry["target"] = target;
ParameterRegistry["current_extremum"] = double.NaN;
}
public override bool CheckCriteria(IRegistry registry, IRegistryResolver resolver)
{
ExtremaTarget target = ParameterRegistry.Get <ExtremaTarget>("target");
string parameter = ParameterRegistry.Get <string>("parameter_identifier");
double value = SimpleDirectEntries[0] ? registry.Get <double>(parameter) : resolver.ResolveGetSingle <double>(parameter);
double currentExtremum = ParameterRegistry.Get <double>("current_extremum");
bool reachedExtremum = target == ExtremaTarget.Min && value <currentExtremum || target == ExtremaTarget.Max && value> currentExtremum;
if (double.IsNaN(currentExtremum) || reachedExtremum)
{
ParameterRegistry["current_extremum"] = value;
return(true);
}
return(false);
}
/// <summary>
/// Create a hook that conditionally (extrema criteria) fetches a given value (i.e. registry identifier) at a given <see cref="ITimeStep"/>.
/// </summary>
/// <param name="valueIdentifier">The value that will be fetched (i.e. registry identifier). E.g. <c>"optimiser.cost_total"</c></param>
/// <param name="timestep">The <see cref="ITimeStep"/> the hook will executed on.</param>
/// <param name="target">The extrema criteria target.</param>
public AccumulatedValueReporter(string valueIdentifier, ITimeStep timestep, ExtremaTarget target) : this(new[] { valueIdentifier }, timestep)
{
On(new ExtremaCriteria(GetAccumulatedIdentifier(valueIdentifier), target));
}
/// <summary>
/// Create a hook that conditionally (extrema criteria) fetches a given value (i.e. registry identifier) at a given <see cref="ITimeStep"/>.
/// </summary>
/// <param name="valueIdentifier">The value that will be fetched (i.e. registry identifier). E.g. <c>"optimiser.cost_total"</c></param>
/// <param name="timestep">The <see cref="ITimeStep"/> the hook will executed on.</param>
/// <param name="target">The extrema criteria target.</param>
public ValueReporter(string valueIdentifier, ITimeStep timestep, ExtremaTarget target) : this(new[] { valueIdentifier }, timestep)
{
On(new ExtremaCriteria(valueIdentifier, target));
}
