/// <summary>
/// Calculate the average distance between the ends of two lines.
/// </summary>
/// <param name="line0">The first line.</param>
/// <param name="line1">The second line.</param>
/// <returns>The shortest average distance between the ends of the lines.</returns>
private static double CalculateAverageDistance(InternalLine line0, InternalLine line1)
{
List <Point> points0 = line0.GetPoints();
List <Point> points1 = line1.GetPoints();
double distfirstfirst = Math.Sqrt(Math.Pow((points0[0].X - points1[0].X), 2) + Math.Pow((points0[0].Y - points1[0].Y), 2));
double distlastlast = Math.Sqrt(Math.Pow((points0.Last().X - points1.Last().X), 2) + Math.Pow((points0.Last().Y - points1.Last().Y), 2));
double distfirstlast = Math.Sqrt(Math.Pow((points0[0].X - points1.Last().X), 2) + Math.Pow((points0[0].Y - points1.Last().Y), 2));
double distlastfirst = Math.Sqrt(Math.Pow((points0.Last().X - points1[0].X), 2) + Math.Pow((points0.Last().Y - points1[0].Y), 2));
if ((distfirstfirst + distlastlast) / 2 < (distfirstlast + distlastfirst) / 2)
{
return((distfirstfirst + distlastlast) / 2);
}
else
{
return((distfirstlast + distlastfirst) / 2);
}
}
/// <summary>
/// An approximate calculation of the average cosine similarity
/// of two lines, achieved by calculating the cosine similarity of subvectors.
/// </summary>
/// <param name="line0">The first line</param>
/// <param name="line1">The second line</param>
/// <returns>The approximate average cosine similarity of all subvectors</returns>
public static double CalculateAverageCosineSimilarity(InternalLine line0, InternalLine line1)
{
//check if one of the lines is a point, or both lines are points
if ((line0.isPoint && !line1.isPoint) || (line1.isPoint && !line0.isPoint))
{
return(0);
}
else if (line0.isPoint && line1.isPoint)
{
return(1);
}
List <Point> points0 = line0.GetPoints();
List <Point> points1 = line1.GetPoints();
if (points0.Count == points1.Count)
{
//If the two lists have an equal amount of subvectors,
//compare the nth subvectors from each list and average the value.
double sum = 0; int i = 0;
List <Point> shortL = points0; List <Point> longL = points1;
for (; i < shortL.Count - 1; i++)
{
if (i + 1 == shortL.Count || i + 1 == longL.Count)
{
break;
}
Vector v0 = new Vector(shortL[i + 1].X - shortL[i].X, shortL[i + 1].Y - shortL[i].Y);
Vector v1 = new Vector(longL[i + 1].X - longL[i].X, longL[i + 1].Y - longL[i].Y);
sum += CosineSimilarity(v0, v1);
}
return(sum / i);
}
else
{
//Determine if the longer list is of similar length or contains significatly more items
List <Point> shortL = points0; List <Point> longL = points0;
if (points0.Count < points1.Count)
{
longL = points1;
}
if (points0.Count > points1.Count)
{
shortL = points1;
}
double dif = (longL.Count - 1) / (shortL.Count - 1);
if (dif > 1)
{
//The longer list is significantly longer
//Each element in the shorter list is compared to multiple
// elements in the longer list to make up the difference
double sum = 0; int adds = 0;
for (int i = 0; i < shortL.Count - 1; i++)
{
if (i + 1 == shortL.Count)
{
break;
}
for (int j = 0; j <= dif; j++)
{
var k = i + j;
if (k + 1 == longL.Count)
{
break;
}
Vector v0 = new Vector(shortL[i + 1].X - shortL[i].X, shortL[i + 1].Y - shortL[i].Y);
Vector v1 = new Vector(longL[k + 1].X - longL[k].X, longL[k + 1].Y - longL[k].Y);
sum += CosineSimilarity(v0, v1); adds++;
}
}
return(sum / adds);
}
else
{
//The longer list is almost the same length as the shorter list
//The remaining items are simply skipped
double sum = 0; int i = 0;
for (; i < shortL.Count - 1; i++)
{
if (i + 1 == shortL.Count || i + 1 == longL.Count)
{
break;
}
Vector v0 = new Vector(shortL[i + 1].X - shortL[i].X, shortL[i + 1].Y - shortL[i].Y);
Vector v1 = new Vector(longL[i + 1].X - longL[i].X, longL[i + 1].Y - longL[i].Y);
sum += CosineSimilarity(v0, v1);
}
return(sum / i);
}
}
}
