/// <summary>
/// Used to calculate the Term Frequency - Inverse Document Frequency of a word.
/// Make sure that the string contains only one word and that it has been processed in the same way your attributes in the GroupToCompare were.
/// </summary>
/// <param name="str">The single word you wish to get a weight for.</param>
/// <param name="GroupToCompare">The group you are using to find it's weight</param>
/// <returns>The weight for the word, higher values means the term is more substantial</returns>
public static double GetTermWeight(this String str, ComparisonGroup GroupToCompare)
{
//Check to see that the term exists in the group
if (GroupToCompare.AttributeFrequency(str) == 0)
{
return(0);
}
//log(N/nt)
return(Math.Log10(1 + GroupToCompare.ItemCount / GroupToCompare.AttributeFrequency(str)));
}
static void Main(string[] args)
{
var wc = new WebClient();
var wizardOfOz = new ComparisonItem(wc.DownloadString("https://www.gutenberg.org/cache/epub/420/pg420.txt").GetWordCount());
var RobinHood = new ComparisonItem(wc.DownloadString("https://www.gutenberg.org/cache/epub/964/pg964.txt").GetWordCount());
var fantasyGroup = new ComparisonGroup()
{
};
fantasyGroup.AddItem(wizardOfOz);
fantasyGroup.AddItem(RobinHood);
var l = "You who so plod amid serious things that you feel it shame to give yourself up even for a few short moments to mirth and joyousness".SearchScore(fantasyGroup);
}
public static List <Tuple <ComparisonItem, Double> > SearchScore(this String search, ComparisonGroup GroupToCompare)
{
return(SearchScore(new ComparisonItem(Processing.WordCount.GetWordCount(search)), GroupToCompare));
}
public static List <Tuple <ComparisonItem, Double> > SearchScore(this ComparisonItem mainItem, ComparisonGroup GroupToCompare)
{
var ret = new List <Tuple <ComparisonItem, Double> >();
//Iterate through the group of items to calculate that items score
foreach (var item in GroupToCompare.Items)
{
//Holds the sum of the score for this item
var sum = 0.0;
//Iterate through each term
foreach (var term in mainItem.Attributes)
{
var itemValue = item.GetValue(term.Key);
var termWeight = GetTermWeight(term.Key, GroupToCompare);
var maxValue = GroupToCompare.MaxAttributeOccurence(term.Key);
//If the term exists
if (maxValue != 0 && itemValue != 0)
{
sum += (itemValue / (maxValue)) * termWeight;
}
}
ret.Add(new Tuple <ComparisonItem, double>(item, sum));
}
return(ret);
}
