/// <summary>
/// Learn <paramref name="k" /> top-ranked FlashFill programs for a given set of input-output examples.
/// </summary>
/// <param name="trainingExamples">
/// The set of input-output examples as a Tuple of the input and the output.
/// </param>
/// <param name="additionalInputs">
/// The set of additional inputs that do not have output examples, which helps rank learnt programs.
/// </param>
/// <param name="k">the number of top programs</param>
/// <returns>The top-k ranked programs as <see cref="FlashFillProg" />s</returns>
public static IEnumerable <FlashFillProg> LearnTopK(IDictionary <string, string> trainingExamples,
IEnumerable <string> additionalInputs = null, int k = 1)
{
if (trainingExamples == null)
{
throw new ArgumentNullException("trainingExamples");
}
// Load FlashFill grammar
Grammar grammar = FlashFillGrammar.Grammar;
// Setup configuration of synthesis process.
var engine = new SynthesisEngine(grammar, new SynthesisEngine.Config
{
// Strategies perform the actual logic of the synthesis process.
Strategies = new[] { typeof(DeductiveSynthesis) },
UseThreads = false,
CacheSize = int.MaxValue
});
// Convert the examples in the format expected by Microsoft.ProgramSynthesis.
// Internally, FlashFill represents strings as StringRegions to save on
// allocating new strings for each substring.
// Could also use FlashFillInput.AsState() to construct the input state.
Dictionary <State, object> trainExamples = trainingExamples.ToDictionary(
t => State.Create(grammar.InputSymbol, new[] { StringRegion.Create(t.Key) }),
t => (object)StringRegion.Create(t.Value));
var spec = new ExampleSpec(trainExamples);
// Learn an entire FlashFill program (i.e. start at the grammar's start symbol)
// for the specificiation consisting of the examples.
// Learn the top-k programs according to the score feature used by FlashFill by default.
// You could define your own feature on the FlashFill grammar to rank programs differently.
var task = new LearningTask(grammar.StartSymbol, spec, k, FlashFillGrammar.ScoreFeature);
if (additionalInputs != null)
{
task.AdditionalInputs =
additionalInputs.Select(
input => State.Create(grammar.InputSymbol, new[] { StringRegion.Create(input) })).ToList();
}
IEnumerable <ProgramNode> topk = engine.LearnSymbol(task).RealizedPrograms;
// Return the generated programs wraped in a FlashFillProg object.
return(topk.Select(prog => new FlashFillProg(prog)));
}