/// <summary>
/// Safely gets all class labels.
/// </summary>
/// <typeparam name="TInstanceSource">The type of a source of instances.</typeparam>
/// <typeparam name="TInstance">The type of an instance.</typeparam>
/// <typeparam name="TLabelSource">The type of a source of labels.</typeparam>
/// <typeparam name="TLabel">The type of a label.</typeparam>
/// <typeparam name="TFeatureValues">The type of the feature values.</typeparam>
/// <param name="mapping">The mapping.</param>
/// <param name="instanceSource">An optional instance source.</param>
/// <param name="labelSource">An optional label source.</param>
/// <returns>All possible values of a label.</returns>
/// <exception cref="MappingException">Thrown if the class labels are null or not unique.</exception>
public static IEnumerable <TLabel> GetClassLabelsSafe <TInstanceSource, TInstance, TLabelSource, TLabel, TFeatureValues>(
this IClassifierMapping <TInstanceSource, TInstance, TLabelSource, TLabel, TFeatureValues> mapping,
TInstanceSource instanceSource = default(TInstanceSource),
TLabelSource labelSource = default(TLabelSource))
{
IEnumerable <TLabel> classLabels = mapping.GetClassLabels(instanceSource, labelSource);
if (classLabels == null)
{
throw new MappingException("The class labels must not be null.");
}
IList <TLabel> classLabelList = classLabels.ToList();
if (classLabelList.Any(label => label == null))
{
throw new MappingException("A class label must not be null.");
}
var classLabelSet = new HashSet <TLabel>(classLabelList);
if (classLabelSet.Count != classLabelList.Count)
{
throw new MappingException("All class labels must be unique.");
}
return(classLabelList);
}
/// <summary>
/// Safely gets all class labels.
/// </summary>
/// <typeparam name="TInstanceSource">The type of a source of instances.</typeparam>
/// <typeparam name="TInstance">The type of an instance.</typeparam>
/// <typeparam name="TLabelSource">The type of a source of labels.</typeparam>
/// <typeparam name="TLabel">The type of a label.</typeparam>
/// <typeparam name="TFeatures">The type of the features.</typeparam>
/// <param name="mapping">The mapping.</param>
/// <param name="instanceSource">An optional instance source.</param>
/// <param name="labelSource">An optional label source.</param>
/// <returns>All possible values of a label.</returns>
/// <exception cref="MappingException">Thrown if the class labels are null, empty, identical or not unique.</exception>
public static IReadOnlyList <TLabel> GetClassLabelsSafe <TInstanceSource, TInstance, TLabelSource, TLabel, TFeatures>(
this IClassifierMapping <TInstanceSource, TInstance, TLabelSource, TLabel, TFeatures> mapping,
TInstanceSource instanceSource = default(TInstanceSource),
TLabelSource labelSource = default(TLabelSource))
{
IEnumerable <TLabel> classLabels = mapping.GetClassLabels(instanceSource, labelSource);
if (classLabels == null)
{
throw new MappingException("The class labels must not be null.");
}
IReadOnlyList <TLabel> classLabelList = classLabels.OrderBy(classLabel => classLabel).ToList();
if (classLabelList.Any(label => label == null))
{
throw new MappingException("A class label must not be null.");
}
var classLabelSet = new HashSet <TLabel>(classLabelList);
int uniqueClassLabelCount = classLabelSet.Count;
if (uniqueClassLabelCount != classLabelList.Count)
{
throw new MappingException("All class labels must be unique.");
}
if (uniqueClassLabelCount < 2)
{
throw new MappingException("There must be at least two distinct class labels.");
}
return(classLabelList);
}