/// <summary>
/// Calculates the f1 score from a confusion matrix
/// </summary>
/// <param name="cm"> confusion matrix metrics</param>
/// <returns> the f1 result</returns>
private static double F1(this ConfusionMatrix cm)
{
var precision = cm.Precision();
var recall = cm.Recall();
var denominator = precision + recall;
return(Math.Abs(denominator) > double.Epsilon ? 2 * (precision * recall) / denominator : 0);
}
/// <summary>
/// Calculates the F<sub>β</sub> score from a confusion matrix.
/// </summary>
/// <param name="matrix">Confusion matrix.</param>
/// <param name="beta">F-measure value.</param>
/// <returns>F<sub>β</sub> score.</returns>
internal static double FScore(this ConfusionMatrix matrix, double beta)
{
var precision = matrix.Precision();
var recall = matrix.Recall();
var denominator = (Math.Pow(beta, 2) * precision) + recall;
return(Math.Abs(denominator) > double.Epsilon ? (1 + Math.Pow(beta, 2)) * (precision * recall) / denominator : 0);
}
/// <summary>
/// Calculates the F<sub>1</sub> score from a confusion matrix.
/// </summary>
/// <param name="matrix">Confusion matrix.</param>
/// <returns>F<sub>1</sub> score.</returns>
internal static double F1(this ConfusionMatrix matrix)
{
var precision = matrix.Precision();
var recall = matrix.Recall();
var denominator = precision + recall;
return(Math.Abs(denominator) > double.Epsilon ? 2 * (precision * recall) / denominator : 0);
}
/// <summary>
/// Calculates Precision, Recall and F1 Score
/// </summary>
/// <param name="cm">confusion matrix metrics</param>
/// <param name="roundingplace"> Specifies the number of digits after the decimal point</param>
/// <returns>List that contains the results calculated</returns>
public static List <double> CalcAccuracy(this ConfusionMatrix cm, int roundingplace = 4)
{
var metrics = new List <double>
{
Math.Round(cm.Precision(), roundingplace),
Math.Round(cm.Recall(), roundingplace),
Math.Round(cm.F1(), roundingplace)
};
return(metrics);
}
/// <summary>
/// Gets the metric value for the given confusion matrix.
/// </summary>
/// <param name="matrix">Confusion matrix.</param>
/// <param name="metric">Metric to compute.</param>
/// <returns>Metric value.</returns>
internal static double GetMetric(this ConfusionMatrix matrix, string metric)
{
if (metric == null)
{
return(matrix.F1());
}
else if (metric == "precision")
{
return(matrix.Precision());
}
else if (metric == "recall")
{
return(matrix.Recall());
}
else if (metric.StartsWith("f", StringComparison.OrdinalIgnoreCase) && double.TryParse(metric.Substring(1), out var beta))
{
return(matrix.FScore(beta));
}
throw new ArgumentOutOfRangeException(nameof(metric), $"Invalid metric value provided.");
}