/// <summary>EP message to <c>str</c>.</summary>
/// <param name="format">Incoming message from <c>format</c>.</param>
/// <param name="args">Incoming message from <c>args</c>.</param>
/// <returns>The outgoing EP message to the <c>str</c> argument.</returns>
/// <remarks>
/// <para>The outgoing message is a distribution matching the moments of <c>str</c> as the random arguments are varied. The formula is <c>proj[p(str) sum_(format,args) p(format,args) factor(str,format,args)]/p(str)</c>.</para>
/// </remarks>
public static StringDistribution StrAverageConditional(StringDistribution format, IList <StringDistribution> args)
{
Argument.CheckIfNotNull(format, "format");
Argument.CheckIfNotNull(args, "args");
Argument.CheckIfValid(args.Count > 0, "args", "There must be at least one argument provided."); // TODO: relax?
if (args.Count >= 10)
{
throw new NotImplementedException("Up to 10 arguments currently supported.");
}
// Disallow special characters in args or format
StringAutomaton result = DisallowBraceReplacersTransducer.ProjectSource(format);
List <StringAutomaton> escapedArgs = args.Select(DisallowBraceReplacersTransducer.ProjectSource).ToList();
// Check braces for correctness and replace them with special characters.
// Also, make sure that each argument placeholder is present exactly once.
// Superposition of transducers is used instead of a single transducer to allow for any order of arguments.
// TODO: in case of a single argument, argument escaping stage can be skipped
for (int i = 0; i < args.Count; ++i)
{
result = GetArgumentEscapingTransducer(i, args.Count, false).ProjectSource(result);
}
// Now replace placeholders with arguments
result = GetPlaceholderReplacingTransducer(escapedArgs, false).ProjectSource(result);
return(StringDistribution.FromWorkspace(result));
}
/// <summary>
/// Tests if a transducer projects each of given strings to a zero function.
/// </summary>
/// <param name="transducer">The transducer.</param>
/// <param name="strings">The strings to test.</param>
public static void TestIfTransducerRejects(StringTransducer transducer, params string[] strings)
{
foreach (string str in strings)
{
var res = transducer.ProjectSource(StringAutomaton.ConstantOn(1.0, str));
Assert.True(res.IsZero());
var res2 = transducer.ProjectSource(str);
Assert.True(res2.IsZero());
}
}
public void CopyElement()
{
StringTransducer copy = StringTransducer.CopyElement(DiscreteChar.OneOf('a', 'b'));
StringInferenceTestUtilities.TestTransducerValue(copy, "a", "a", 1.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "b", "b", 1.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "a", "b", 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "b", "a", 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, string.Empty, string.Empty, 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "bb", "bb", 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "bab", "bab", 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "bab", "ba", 0.0);
//// Tests that projection on CopyElement(elements) shrinks the support
StringAutomaton automaton = StringAutomaton.ConstantOn(2.0, "a", "ab", "ac");
automaton = automaton.Sum(StringAutomaton.ConstantOn(1.0, "a"));
automaton = automaton.Sum(StringAutomaton.Constant(2.0));
automaton = automaton.Product(StringAutomaton.Constant(3.0));
for (int i = 0; i < 2; ++i)
{
StringInferenceTestUtilities.TestValue(automaton, 15, "a");
StringInferenceTestUtilities.TestValue(automaton, 6.0, "b");
StringInferenceTestUtilities.TestValue(automaton, i == 0 ? 6.0 : 0.0, string.Empty);
StringInferenceTestUtilities.TestValue(automaton, i == 0 ? 12.0 : 0.0, "ac", "ab");
automaton = copy.ProjectSource(automaton);
}
}
public void Copy()
{
StringTransducer copy = StringTransducer.Copy();
StringInferenceTestUtilities.TestTransducerValue(copy, "important", "important", 1.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "important", "i", 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "important", "imp", 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "important", "t", 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "important", "mpo", 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, string.Empty, string.Empty, 1.0);
StringInferenceTestUtilities.TestTransducerValue(copy, "important", string.Empty, 0.0);
StringInferenceTestUtilities.TestTransducerValue(copy, string.Empty, "important", 0.0);
//// Test that projection on Copy() doesn't change the automaton
StringAutomaton automaton = StringAutomaton.ConstantOn(2.0, "a", "ab", "ac");
automaton = automaton.Sum(StringAutomaton.ConstantOn(1.0, "a"));
automaton = automaton.Sum(StringAutomaton.Constant(2.0));
automaton = automaton.Product(StringAutomaton.Constant(3.0));
StringAutomaton automatonClone = copy.ProjectSource(automaton);
Assert.Equal(automaton, automatonClone);
}
/// <summary>
/// Computes the normalizer via transducers.
/// </summary>
/// <param name="automaton">The automaton.</param>
/// <returns>The logarithm of the normalizer.</returns>
private static double GetLogNormalizerByGetValueWithTransducers(StringAutomaton automaton)
{
var one = StringAutomaton.Constant(1.0);
StringTransducer transducer = StringTransducer.Consume(automaton);
transducer.AppendInPlace(StringTransducer.Produce(one));
return(transducer.ProjectSource(one).GetLogValue("an arbitrary string")); // Now this will be exactly the normalizer
}
/// <summary>
/// Tests if a projection of a given automaton onto a given transducer has the desired value on a given sequence.
/// </summary>
/// <param name="transducer">The transducer.</param>
/// <param name="input">The automaton to project.</param>
/// <param name="str">The sequence to test the projection on.</param>
/// <param name="trueValue">The desired value of the projection on the sequence.</param>
public static void TestTransducerProjection(
StringTransducer transducer, StringAutomaton input, string str, double trueValue)
{
// Test ProjectSource(func)
var result = transducer.ProjectSource(input);
TestValue(result, trueValue, str);
}
/// <summary>EP message to <c>str2</c>.</summary>
/// <param name="concat">Incoming message from <c>concat</c>.</param>
/// <param name="str1">Incoming message from <c>str1</c>.</param>
/// <returns>The outgoing EP message to the <c>str2</c> argument.</returns>
/// <remarks>
/// <para>The outgoing message is a distribution matching the moments of <c>str2</c> as the random arguments are varied. The formula is <c>proj[p(str2) sum_(concat,str1) p(concat,str1) factor(concat,str1,str2)]/p(str2)</c>.</para>
/// </remarks>
public static StringDistribution Str2AverageConditional(StringDistribution concat, StringDistribution str1)
{
Argument.CheckIfNotNull(concat, "concat");
Argument.CheckIfNotNull(str1, "str1");
StringTransducer transducer = StringTransducer.Consume(str1.GetProbabilityFunction());
transducer.AppendInPlace(StringTransducer.Copy());
return(StringDistribution.FromWorkspace(transducer.ProjectSource(concat)));
}
/// <include file='FactorDocs.xml' path='factor_docs/message_op_class[@name="StringConcatOp"]/message_doc[@name="Str1AverageConditional(StringDistribution, StringDistribution)"]/*'/>
public static StringDistribution Str1AverageConditional(StringDistribution concat, StringDistribution str2)
{
Argument.CheckIfNotNull(concat, "concat");
Argument.CheckIfNotNull(str2, "str2");
StringTransducer transducer = StringTransducer.Copy();
transducer.AppendInPlace(StringTransducer.Consume(str2.ToAutomaton()));
return(StringDistribution.FromWeightFunction(transducer.ProjectSource(concat.ToAutomaton())));
}
/// <include file='FactorDocs.xml' path='factor_docs/message_op_class[@name="StringConcatOp"]/message_doc[@name="Str1AverageConditional(StringDistribution, StringDistribution)"]/*'/>
public static StringDistribution Str1AverageConditional(StringDistribution concat, StringDistribution str2)
{
Argument.CheckIfNotNull(concat, "concat");
Argument.CheckIfNotNull(str2, "str2");
StringTransducer transducer = StringTransducer.Copy();
transducer.AppendInPlace(StringTransducer.Consume(str2.GetWorkspaceOrPoint()));
return(StringDistribution.FromWorkspace(transducer.ProjectSource(concat.GetWorkspaceOrPoint())));
}
/// <summary>
/// Tests if a transducer has the desired value on a given pair of strings.
/// </summary>
/// <param name="transducer">The transducer.</param>
/// <param name="string1">The first string.</param>
/// <param name="string2">The second string.</param>
/// <param name="trueValue">The desired value of the transducer on the strings.</param>
public static void TestTransducerValue(
StringTransducer transducer, string string1, string string2, double trueValue)
{
// Test ProjectSource(sequence)
var result = transducer.ProjectSource(string1);
TestValue(result, trueValue, string2);
// Test ProjectSource(func)
TestTransducerProjection(transducer, StringAutomaton.ConstantOn(1.0, string1), string2, trueValue);
// Test GetValue()
double value = transducer.GetValue(string1, string2);
Assert.Equal(trueValue, value, LogValueEps);
}
public void CopySequence2()
{
const int CopyCount = 10;
const int LetterCount = 20;
StringTransducer copy = StringTransducer.Copy();
for (int i = 0; i < CopyCount - 1; ++i)
{
copy.AppendInPlace(StringTransducer.Copy());
}
var sequence = new string(Enumerable.Repeat('a', LetterCount).ToArray());
StringAutomaton result = copy.ProjectSource(sequence);
var expectedLogValue = Math.Log(StringInferenceTestUtilities.Partitions(LetterCount, CopyCount));
Assert.Equal(expectedLogValue, result.GetLogValue(sequence), 1e-8);
}
