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public static Sum ( |
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| v | A variable-length parameters list containing v. | |
| return | double | |
/// <summary>
/// A Vector extension method that determines the mean of the given parameters.
/// </summary>
/// <exception cref="InvalidOperationException">Thrown when the requested operation is invalid.</exception>
/// <param name="source">The source to act on.</param>
/// <returns>The mean value.</returns>
public static double Mean(this Vector source)
{
if (source.Length == 0)
{
throw new InvalidOperationException("Cannot compute average of an empty vector.");
}
return(source.Sum() / source.Length);
}
/// <summary>Computes.</summary>
/// <exception cref="InvalidOperationException">Thrown when the requested operation is invalid.</exception>
/// <param name="x">The Vector to process.</param>
/// <param name="y">The Vector to process.</param>
/// <returns>A double.</returns>
public double Compute(Vector x, Vector y)
{
if (x.Length != y.Length)
throw new InvalidOperationException("Cannot compute similarity between two unequally sized Vectors!");
var xSum = x.Sum();
var ySum = y.Sum();
var xElem = (x^2).Sum() - ((xSum * xSum) / x.Length);
var yElem = (y^2).Sum() - ((ySum * ySum) / y.Length);
return (x.Dot(y) - ((xSum * ySum) / x.Length)) / System.Math.Sqrt(xElem * yElem);
}
/// <summary>
/// Normalizes the values so that the sum of all values is 1.
/// <para>Values should be positive prior to normalization for correctness.</para>
/// </summary>
/// <param name="v">Vector to normalize.</param>
/// <returns>Vector.</returns>
public static Vector Normalize(this Vector v)
{
double sum = v.Sum();
if (sum == 0)
{
throw new InvalidOperationException("Cannot normalize a zero sequence.");
}
Vector v_t = v.Each(d => d / sum, true);
return(v_t);
}
/// <summary>An IEnumerable<Vector> extension method that sums the given source.</summary>
/// <param name="v">The v to act on.</param>
/// <returns>A Vector.</returns>
public static double Sum(this Vector v)
{
return(Vector.Sum(v));
}
