/// <summary>
/// Calculates the priority based on the frequency that the character changed to in the candidate word is the 'changed from' character in a substitution between adjacent words.
/// </summary>
/// <param name="currentWord">The current word being traversed from.</param>
/// <param name="candidateWord">The candidate word to calculate the priority for.</param>
/// <param name="destinationWord">The destination word.</param>
/// <param name="distanceFromSourceToCandidateWord">The distance (in graph edges) from the source word, to the candidate word.</param>
/// <returns>The priority.</returns>
protected Double CalculatePopularityOfChangeToCharacterPriority(String currentWord, String candidateWord, String destinationWord, Int32 distanceFromSourceToCandidateWord)
{
Char changeToCharacter = wordUtilities.FindDifferingCharacters(currentWord, candidateWord).Item2;
Int32 fromCharacterFrequency = fromCharacterFrequencies.GetFrequency(changeToCharacter);
return(1.0 - (Convert.ToDouble(fromCharacterFrequency) / Convert.ToDouble(maximumFromCharacterFrequency)));
}
/// <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));
}
}
}