public override double CalculateDocumentLogProbability(Corpus testCorpus)
{
double corpusLogP = 0.0;
// Sentence probability = multiplication of all words probabilities
foreach (var sentence in testCorpus.AllTokenizedSentences)
{
// Initialize x_{-1}, x_{-2} to START
var u = "<s>";
var v = "<s>";
double logPs = 0.0;
foreach (var w in sentence)
{
double qWuv = ComputeWordProbability(u, v, w);
// Add to sentence probability
logPs += Math.Log2(qWuv);
// Replace previous tokens
u = v;
v = w;
}
corpusLogP += logPs;
}
return(corpusLogP);
}
public override void TrainLanguageModel(Corpus trainingCorpus)
{
// Since we interpolate all three q's for every n-gram, preparing this model means preparing all the base n-gram models
this.UnigramLM.TrainLanguageModel(trainingCorpus);
this.BigramLM.TrainLanguageModel(trainingCorpus);
this.TrigramLM.TrainLanguageModel(trainingCorpus);
}
public static void AddStopTokens(Corpus corpus)
{
foreach (var line in corpus.AllTokenizedSentences)
{
line.Add("</s>");
}
;
corpus.ComputeTotalWordsCount();
}
public static void UnkCorpus(Corpus corpus, HashSet <string> validVocabulary)
{
foreach (var line in corpus.AllTokenizedSentences)
{
for (var i = 0; i < line.Count; i++)
{
if (!validVocabulary.Contains(line[i]))
{
line[i] = "<unk>";
}
}
}
;
}
public static HashSet <string> GetValidVocabulary(Corpus corpus, double unkRatio)
{
// Implement a naive unk strategy: unk top n% of lowest count words
// TODO parametize the strategy
// Order by word count, then alphabetically to ensure determinism TODO I may want to randomize
var uniqueSortedTokens = corpus.AllTokenizedSentences.SelectMany(s => s).GroupBy(w => w).OrderByDescending(g => g.Count()).ThenBy(g => g.Key);
// Remove n% of words
var ratioToKeep = 1.0 - unkRatio;
var wordsToKeep = (int)Math.Floor(uniqueSortedTokens.Count() * ratioToKeep);
var validVocabulary = uniqueSortedTokens.Take(wordsToKeep).Select(g => g.Key).ToHashSet();
return(validVocabulary);
}
public override void TrainLanguageModel(Corpus trainingCorpus)
{
// We are fine flattening all setences into one big string as every word probability is independent of any previous one, so no risk on wrapping sentences
// Enumerate once so we don't keep on doing it later on
var flattenedTokenizedAndProcessedSentences = trainingCorpus.AllTokenizedSentences.SelectMany(s => s).ToList();
// Add n-gram counts (used in numerator)
this.NGramCounts = flattenedTokenizedAndProcessedSentences.GroupBy(w => w).ToDictionary(g => new Unigram {
w = g.Key
}.GetComparisonKey(), g => g.Count());
this.UniqueNGramsCount = NGramCounts.Count;
// Add n-1-gram counts (used in denominator)
// In the case of unigrams, we care about total token counts, including STOP tokens
this.NGramCounts[new Unigram {
w = string.Empty
}.GetComparisonKey()] = trainingCorpus.TotalWordsCount;
}
public override void TrainLanguageModel(Corpus trainingCorpus)
{
// We need to process sentece by sentence to avoid wrapping sentences, ie. counting (STOP, v, w) trigrams
foreach (var sentence in trainingCorpus.AllTokenizedSentences)
{
// Initialize x_{-1}, x_{-2} to START
var u = "<s>";
var v = "<s>";
// We now need to store all counts of c(u, v, w) and c(v, w)
foreach (var w in sentence)
{
Bigram uvBigram = new Bigram {
v = u, w = v
};
Trigram uvwTrigram = new Trigram {
u = u, v = v, w = w
};
// +1 to current count, current will be 0 if not found, thus starting at 1 as expected
this.NGramCounts.TryGetValue(uvBigram.GetComparisonKey(), out int uvCount);
uvCount++;
this.NGramCounts[uvBigram.GetComparisonKey()] = uvCount;
var isNewNgram = !this.NGramCounts.TryGetValue(uvwTrigram.GetComparisonKey(), out int uvwCount);
uvwCount++;
this.NGramCounts[uvwTrigram.GetComparisonKey()] = uvwCount;
if (isNewNgram)
{
this.UniqueNGramsCount++;
}
// Replace previous tokens
u = v;
v = w;
}
}
}
public override double CalculateDocumentLogProbability(Corpus testCorpus)
{
double corpusLogP = 0.0;
// Sentence probability = multiplication of all words probabilities
foreach (var sentence in testCorpus.AllTokenizedSentences)
{
double logPs = 0.0;
foreach (var w in sentence)
{
double qW = ComputeWordProbability(string.Empty, string.Empty, w);
// Add to sentence probability
logPs += Math.Log2(qW);
}
corpusLogP += logPs;
}
return(corpusLogP);
}
private static void TrainAllLanguageModels(LanguageModelHyperparameters hyperparameters, string crossValIterationPath, Corpus preProcessedCollectionCorpus)
{
var stopwatch = new Stopwatch();
var i = 1;
foreach (var categoryLanguageModel in hyperparameters.CategoryNGramLanguageModelsMap.Append(new KeyValuePair <string, INGramLanguageModel>("ALLCATEGORIES", hyperparameters.CollectionLevelLanguageModel)))
{
var category = categoryLanguageModel.Key;
var languageModel = categoryLanguageModel.Value;
stopwatch.Restart();
Corpus preProcessedCategoryTrainingCorpus;
if (category.Equals("ALLCATEGORIES"))
{
preProcessedCategoryTrainingCorpus = preProcessedCollectionCorpus;
}
else
{
preProcessedCategoryTrainingCorpus = new Corpus();
preProcessedCategoryTrainingCorpus.InitializeAndPreprocessCategoryCorpus(Path.Combine(crossValIterationPath, "training"), category, hyperparameters);
}
TextProcessingUtilities.UnkCorpus(preProcessedCategoryTrainingCorpus, Corpus.ValidVocabulary);
TextProcessingUtilities.AddStopTokens(preProcessedCategoryTrainingCorpus);
languageModel.TrainLanguageModel(preProcessedCategoryTrainingCorpus);
stopwatch.Stop();
//Console.WriteLine($@"LanguageModel for category {category} trained in {stopwatch.ElapsedMilliseconds} ms. {i}/{hyperparameters.CategoryNGramLanguageModelsMap.Count} done");
i++;
}
}
static void Main(string[] args)
{
var appConfigName = "app.config";
try
{
if (!File.Exists(Path.Combine(args[0], appConfigName)))
{
Console.WriteLine($"{appConfigName} not found in {args[0]}");
}
}
catch (Exception)
{
Console.WriteLine($"{appConfigName} not found in {args[0]}");
}
var configPath = args[0];
var allRuns = File.ReadAllLines(Path.Combine(configPath, appConfigName)).Where(s => !string.IsNullOrWhiteSpace(s) && !s.StartsWith("##"));
string dataset = args.Length > 1 && args[1].ToLower().Equals("-usesongs") ? "songs" : "reuters";
string datasetCrossValRootPath = Path.Combine(configPath, @$ "Dataset/{dataset}/CrossVal/");
int crossValidationValue = new DirectoryInfo(datasetCrossValRootPath).GetDirectories().Length;
for (int i = 0; i < crossValidationValue; i++)
{
Console.WriteLine($@"Cross validation iteration {i + 1}");
var allHyperparameters = allRuns.Select(r => LanguageModelHyperparameters.GenerateFromArguments(r));
var crossValIterationPath = Path.Combine(datasetCrossValRootPath, @$ "{i + 1}");
// Our corpus existing classification is independent of training
Corpus.InitializeAndFillCategoriesMap(crossValIterationPath);
NaiveBayesClassifier.InitializeAndFillCategoryTrainingCounts(Corpus.CategoriesMap);
// Delete previous predictions files
var dir = new DirectoryInfo(crossValIterationPath);
foreach (var file in dir.EnumerateFiles("predictions*"))
{
file.Delete();
}
var runId = 1;
foreach (var hyperparameters in allHyperparameters)
{
var globalStopwatch = new Stopwatch();
globalStopwatch.Start();
// We do this here as volcabulary can change depending on hyperparams
//Console.WriteLine($@"Parsing all training documents to get valid vocabulary and train collection level unigram model (used by some smoothing techniques)...");
var allCategoriesTrainingCorpus = new Corpus();
allCategoriesTrainingCorpus.InitializeAndPreprocessCategoryCorpus(Path.Combine(crossValIterationPath, "training"), "ALLCATEGORIES", hyperparameters);
Corpus.InitializeAndFillValidVocabulary(allCategoriesTrainingCorpus, hyperparameters);
//Console.WriteLine($@"Generated valid vocabulary. Elapsed time: {globalStopwatch.ElapsedMilliseconds}");
TrainAllLanguageModels(hyperparameters, crossValIterationPath, allCategoriesTrainingCorpus);
//Console.WriteLine();
//Console.WriteLine($@"Training done in {globalStopwatch.ElapsedMilliseconds} ms");
//Console.WriteLine();
//Console.WriteLine($@"Classifying documents");
var allPredictions = ClassifyAllTestDocuments(hyperparameters, crossValIterationPath);
File.WriteAllLines(Path.Combine(crossValIterationPath, @$ "predictions{runId}"), allPredictions);
//Console.WriteLine($@"Elapsed time: {globalStopwatch.ElapsedMilliseconds} ms");
runId++;
}
}
}
public abstract double CalculateDocumentLogProbability(Corpus corpus);
public abstract void TrainLanguageModel(Corpus corpus);
