/// <summary>
/// Reads a set of words from a stream, and adds the words and statistics pertaining to the words to a set of data structures.
/// </summary>
/// <param name="reader">The stream reader to used to read the set of words (allows specifying a mocked reader for unit testing).</param>
/// <param name="trieBuilder">The trie builder to use to add the words to the trie (allows specifying a mocked builder for unit testing).</param>
/// <param name="wordFilterFunction">A Func to filter whether or not the specified word should be added to the trie. Accepts the word as a parameter, and returns a bookean indicating whether that word should be added to the trie.</param>
/// <param name="allWordsTrieRoot">The root of a character trie to populate with the words.</param>
/// <param name="allWords">A HashSet to populate with the words.</param>
/// <param name="fromCharacterFrequencies">A FrequencyTable to populate with the number of times each character is the 'from' character in a substitution.</param>
/// <param name="characterSubstitutionFrequencies">A FrequencyTable to populate with the number of times each pair of characters in a substitution occur.</param>
public void PopulateAdjacentWordDataStructures(IStreamReader reader, ICharacterTrieBuilder trieBuilder, Func <String, Boolean> wordFilterFunction, Dictionary <Char, TrieNode <Char> > allWordsTrieRoot, HashSet <String> allWords, FrequencyTable <Char> fromCharacterFrequencies, FrequencyTable <CharacterSubstitution> characterSubstitutionFrequencies)
{
// Read all words and add them to the HashSet and trie
using (reader)
{
while (reader.EndOfStream == false)
{
String currentWord = reader.ReadLine();
if (wordFilterFunction.Invoke(currentWord) == true)
{
if (allWords.Contains(currentWord) == false)
{
allWords.Add(currentWord);
trieBuilder.AddWord(allWordsTrieRoot, currentWord, true);
}
}
}
}
// Populate the frequency tables
CharacterTrieUtilities trieUtilities = new CharacterTrieUtilities();
WordUtilities wordUtilities = new WordUtilities();
foreach (String currentWord in allWords)
{
foreach (String adjacentWord in trieUtilities.FindAdjacentWords(allWordsTrieRoot, currentWord))
{
// Find the character which was substitued between the word and the adjacent word
Tuple <Char, Char> differingCharacters = wordUtilities.FindDifferingCharacters(currentWord, adjacentWord);
Char fromCharacter = differingCharacters.Item1, toCharacter = differingCharacters.Item2;
// Increment the data structures
fromCharacterFrequencies.Increment(fromCharacter);
characterSubstitutionFrequencies.Increment(new CharacterSubstitution(fromCharacter, toCharacter));
}
}
}
/// <summary>
/// Initialises a new instance of the Algorithms.AdjacentWordGraphPathFinder class.
/// </summary>
/// <param name="priorityCalculator">Used to calculate the priority assigned to candidate words.</param>
/// <param name="trieUtilities">Used to find adjacent vertices in the graph of words.</param>
/// <param name="wordDictionaryTrieRoot">The root node of a character trie containing all the words in the graph.</param>
/// <remarks>Note that parameter 'wordDictionaryTrieRoot' should be the same character trie root that is set on the constructor of parameter 'priorityCalculator'.</remarks>
public AdjacentWordGraphPathFinder(CandidateWordPriorityCalculator priorityCalculator, CharacterTrieUtilities trieUtilities, Dictionary <Char, TrieNode <Char> > wordDictionaryTrieRoot)
{
this.priorityCalculator = priorityCalculator;
this.trieUtilities = trieUtilities;
this.wordDictionaryTrieRoot = wordDictionaryTrieRoot;
}
/// <summary>
/// Runs the graph traversal comparison.
/// </summary>
public void Run()
{
// The path to a file containing a dictionary of words
const String dictionaryFilePath = @"C:\Temp\words2.txt";
// The assumed maximum distance from a source word to a candidate word (used in weighting of g(n) and h(n) scores)
const Int32 maximumSourceWordToCandidateWordDistance = 30;
// Setup the word dictionary tree and other supporting data structures
Dictionary <Char, TrieNode <Char> > allWordsTrieRoot = new Dictionary <Char, TrieNode <Char> >();
HashSet <String> allWords = new HashSet <String>();
FrequencyTable <Char> fromCharacterFrequencies = new FrequencyTable <Char>();
FrequencyTable <CharacterSubstitution> characterSubstitutionFrequencies = new FrequencyTable <CharacterSubstitution>();
// Populate the word dictionary tree and other supporting data structures
System.IO.StreamReader underlyingReader = new System.IO.StreamReader(dictionaryFilePath);
Algorithms.StreamReader reader = new Algorithms.StreamReader(underlyingReader);
CharacterTrieBuilder trieBuilder = new CharacterTrieBuilder();
Func <String, Boolean> wordFilterFunction = new Func <String, Boolean>((inputString) =>
{
foreach (Char currentCharacter in inputString)
{
if (Char.IsLetter(currentCharacter) == false)
{
return(false);
}
}
if (inputString.Length == 4)
{
return(true);
}
else
{
return(false);
}
});
DataStructureUtilities dataStructureUtils = new DataStructureUtilities();
dataStructureUtils.PopulateAdjacentWordDataStructures(reader, trieBuilder, wordFilterFunction, allWordsTrieRoot, allWords, fromCharacterFrequencies, characterSubstitutionFrequencies);
CharacterTrieUtilities trieUtilities = new CharacterTrieUtilities();
// Setup the test data (word pairs to find paths between)
List <Tuple <String, String> > testData = new List <Tuple <String, String> >()
{
new Tuple <String, String>("role", "band"),
new Tuple <String, String>("pack", "sill"),
new Tuple <String, String>("debt", "tyre"),
new Tuple <String, String>("duct", "grid")
};
// Find paths
foreach (Tuple <String, String> currentWordPair in testData)
{
// Setup priority calculator and graph path finder
Int32 sourceWordToCandidateWordDistanceWeight = 1;
Int32 numberOfCharactersMatchingDestinationWeight = 0;
Int32 popularityOfChangeToCharacterWeight = 0;
Int32 popularityOfCharacterChangeWeight = 0;
CandidateWordPriorityCalculator priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
AdjacentWordGraphPathFinder pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
Console.WriteLine("-----------------------------------------------");
Console.WriteLine(" Finding paths for strings '{0}' and '{1}'", currentWordPair.Item1, currentWordPair.Item2);
Console.WriteLine("-----------------------------------------------");
// Find a path using breadth-first search
Console.WriteLine(" Using breadth-first search...");
Int32 numberOfEdgesExplored = 0;
LinkedList <String> path = pathFinder.FindPathViaAStar(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine();
// Find the shortest path using Dijkstras algorithm
Console.WriteLine(" Using Dijkstra's algorithm...");
numberOfEdgesExplored = 0;
path = pathFinder.FindShortestPathViaDijkstrasAlgorithm(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine();
// Find the shortest path using bidirectional breadth-first search
Console.WriteLine(" Using bidirectional breadth-first search...");
numberOfEdgesExplored = 0;
path = pathFinder.FindPathViaBidirectionalBreadthFirstSearch(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine();
// Find the shortest path using A* ( 50% g(n) and 50% h(n) )
Console.WriteLine(" Using A* ( 50% g(n) and 50% h(n) )...");
sourceWordToCandidateWordDistanceWeight = 3;
numberOfCharactersMatchingDestinationWeight = 1;
popularityOfChangeToCharacterWeight = 1;
popularityOfCharacterChangeWeight = 1;
priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
numberOfEdgesExplored = 0;
path = pathFinder.FindPathViaAStar(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine();
// Find the shortest path using A* ( 0% g(n) and 100% h(n) )
Console.WriteLine(" Using A* ( 0% g(n) and 100% h(n) )...");
sourceWordToCandidateWordDistanceWeight = 0;
numberOfCharactersMatchingDestinationWeight = 1;
popularityOfChangeToCharacterWeight = 1;
popularityOfCharacterChangeWeight = 1;
priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
numberOfEdgesExplored = 0;
path = pathFinder.FindPathViaAStar(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine();
// Find the shortest path using A* ( 25% g(n) and 75% h(n) )
Console.WriteLine(" Using A* ( 25% g(n) and 75% h(n) )...");
sourceWordToCandidateWordDistanceWeight = 1;
numberOfCharactersMatchingDestinationWeight = 1;
popularityOfChangeToCharacterWeight = 1;
popularityOfCharacterChangeWeight = 1;
priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
numberOfEdgesExplored = 0;
path = pathFinder.FindPathViaAStar(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine();
// Find the shortest path using A* ( 25% g(n) and 75% h(n) with custom h(n) weighting )
Console.WriteLine(" Using A* ( 25% g(n) and 75% h(n) with custom h(n) weighting )...");
sourceWordToCandidateWordDistanceWeight = 1;
numberOfCharactersMatchingDestinationWeight = 2;
popularityOfChangeToCharacterWeight = 1;
popularityOfCharacterChangeWeight = 0;
priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
numberOfEdgesExplored = 0;
path = pathFinder.FindPathViaAStar(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine();
Console.WriteLine();
}
return;
#region Test Code and Utility Routines
// Read a word from the console and find its adjacent words
String readWord = "";
while (true)
{
Console.Write("Type a source word: ");
readWord = Console.ReadLine();
if (readWord.Equals("q"))
{
break;
}
foreach (String currAdjacent in trieUtilities.FindAdjacentWords(allWordsTrieRoot, readWord))
{
Console.WriteLine(" " + currAdjacent);
}
}
// Find the total number of edges and vertices in the graph
Int32 totalEdges = 0;
foreach (String currWord in allWords)
{
foreach (String currAdj in trieUtilities.FindAdjacentWords(allWordsTrieRoot, currWord))
{
totalEdges++;
}
}
Console.WriteLine("Total edges: " + totalEdges / 2);
Console.WriteLine("Total vertices: " + allWords.Count);
// Show contents of frequency tables
foreach (KeyValuePair <Char, Int32> currKVP in fromCharacterFrequencies)
{
Console.WriteLine(currKVP.Key + ": " + currKVP.Value);
}
Console.WriteLine("t > b: " + characterSubstitutionFrequencies.GetFrequency(new CharacterSubstitution('t', 'b')));
Console.WriteLine("n > f: " + characterSubstitutionFrequencies.GetFrequency(new CharacterSubstitution('n', 'f')));
foreach (KeyValuePair <CharacterSubstitution, Int32> currKVP in characterSubstitutionFrequencies)
{
if (currKVP.Key.ToCharacter == 'y')
{
Console.WriteLine(currKVP.Key.FromCharacter + " > " + currKVP.Key.ToCharacter + ": " + currKVP.Value);
}
}
foreach (String currWord in allWords)
{
if (currWord[1] == 'y')
{
Console.WriteLine(currWord);
}
}
// Compare each heuristic function in isolation
List <Tuple <String, String> > testData2 = new List <Tuple <String, String> >()
{
new Tuple <String, String>("role", "band"),
new Tuple <String, String>("pack", "sill"),
new Tuple <String, String>("debt", "tyre"),
new Tuple <String, String>("duct", "grid")
};
foreach (Tuple <String, String> currentWordPair in testData2)
{
// Setup priority calculator and graph path finder
Int32 sourceWordToCandidateWordDistanceWeight = 1;
Int32 numberOfCharactersMatchingDestinationWeight = 0;
Int32 popularityOfChangeToCharacterWeight = 0;
Int32 popularityOfCharacterChangeWeight = 0;
CandidateWordPriorityCalculator priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
AdjacentWordGraphPathFinder pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
Int32 numberOfEdgesExplored = 0;
Int32 maximumSourceWordToCandidateWordDistance2 = 4000;
Console.WriteLine("-----------------------------------------------");
Console.WriteLine(" Finding paths for strings '{0}' and '{1}'", currentWordPair.Item1, currentWordPair.Item2);
Console.WriteLine("-----------------------------------------------");
// Find the shortest path using A* ( 50% g(n) and 50% h(n) )
Console.WriteLine(" 1 0 0...");
sourceWordToCandidateWordDistanceWeight = 0;
numberOfCharactersMatchingDestinationWeight = 1;
popularityOfChangeToCharacterWeight = 0;
popularityOfCharacterChangeWeight = 0;
priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance2, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
numberOfEdgesExplored = 0;
LinkedList <String> path = pathFinder.FindPathViaAStar(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine(" Length of path: {0}", path.Count);
Console.WriteLine();
// Find the shortest path using A* ( 0% g(n) and 100% h(n) )
Console.WriteLine(" 0 1 0...");
sourceWordToCandidateWordDistanceWeight = 0;
numberOfCharactersMatchingDestinationWeight = 0;
popularityOfChangeToCharacterWeight = 1;
popularityOfCharacterChangeWeight = 0;
priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance2, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
numberOfEdgesExplored = 0;
path = pathFinder.FindPathViaAStar(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine(" Length of path: {0}", path.Count);
Console.WriteLine();
// Find the shortest path using A* ( 25% g(n) and 75% h(n) )
Console.WriteLine(" 0 0 1...");
sourceWordToCandidateWordDistanceWeight = 0;
numberOfCharactersMatchingDestinationWeight = 0;
popularityOfChangeToCharacterWeight = 0;
popularityOfCharacterChangeWeight = 1;
priorityCalculator = new CandidateWordPriorityCalculator(maximumSourceWordToCandidateWordDistance2, sourceWordToCandidateWordDistanceWeight, numberOfCharactersMatchingDestinationWeight, popularityOfChangeToCharacterWeight, popularityOfCharacterChangeWeight, allWordsTrieRoot, fromCharacterFrequencies, characterSubstitutionFrequencies);
pathFinder = new AdjacentWordGraphPathFinder(priorityCalculator, trieUtilities, allWordsTrieRoot);
numberOfEdgesExplored = 0;
path = pathFinder.FindPathViaAStar(currentWordPair.Item1, currentWordPair.Item2, ref numberOfEdgesExplored);
Console.Write(" Path: ");
WritePathToConsole(path);
Console.WriteLine(" Edges explored: {0}", numberOfEdgesExplored);
Console.WriteLine(" Length of path: {0}", path.Count);
Console.WriteLine();
Console.WriteLine();
}
#endregion
}
