/// <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.");
}
/// <summary>
/// Calculates the precision from a confusion matrix
/// </summary>
/// <param name="cm">confusion matrix metrics</param>
/// <returns>The precision result</returns>
private static double Precision(this ConfusionMatrix cm)
{
return(Divide(cm.TruePositive, cm.TruePositive + cm.FalsePositive));
}
/// <summary>
/// Calculates the recall from a confusion matrix
/// </summary>
/// <param name="cm"> confusin matrix metrics</param>
/// <returns> The recall result</returns>
private static double Recall(this ConfusionMatrix cm)
{
return(Divide(cm.TruePositive, cm.TruePositive + cm.FalseNegative));
}
/// <summary>
/// Calculates total count for the confusion matrix.
/// </summary>
/// <param name="matrix">Confusion matrix.</param>
/// <returns>Total count.</returns>
internal static int Total(this ConfusionMatrix matrix)
{
return(matrix.TruePositive + matrix.TrueNegative + matrix.FalsePositive + matrix.FalseNegative);
}
/// <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)
{
return(matrix.FScore(1));
}
/// <summary>
/// Calculates the recall from a confusion matrix.
/// </summary>
/// <param name="matrix">Confusion matrix.</param>
/// <returns>Recall value.</returns>
internal static double Recall(this ConfusionMatrix matrix)
{
return(Divide(matrix.TruePositive, matrix.TruePositive + matrix.FalseNegative));
}
/// <summary>
/// Calculates the precision from a confusion matrix.
/// </summary>
/// <param name="matrix">Confusion matrix.</param>
/// <returns>Precision value.</returns>
internal static double Precision(this ConfusionMatrix matrix)
{
return(Divide(matrix.TruePositive, matrix.TruePositive + matrix.FalsePositive));
}