/// <summary>
/// Classifies a sequence of elements using the features extracted from each element,
/// and monitors cancellation requests.
/// </summary>
/// <typeparam name="T">The type of the elements to classify.</typeparam>
/// <param name="sources">The elements to classify.</param>
/// <param name="selector">The selector that converts elements into <typeparamref name="TFeatures"/> objects.</param>
/// <param name="progress">The provider used to report a progress change. Can be <b>null</b>.</param>
/// <param name="cancellationToken">The cancellationToken token used to notify the classifier that the operation should be canceled.</param>
/// <returns>
/// The sequence of <see cref="Answer"/> objects that contains the classification results.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <para><paramref name="sources"/> is <b>null</b>.</para>
/// <para>-or-</para>
/// <para><paramref name="selector"/> is <b>null</b>.</para>
/// </exception>
public IEnumerable <Answer> Classify <T>(
IEnumerable <T> sources,
Func <T, CancellationToken, TFeatures> selector,
IClassifierProgress <T> progress,
CancellationToken cancellationToken)
{
if (sources == null)
{
throw new ArgumentNullException(nameof(sources));
}
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
return(sources
.AsParallel()
.AsOrdered()
.WithCancellation(cancellationToken)
.WithMergeOptions(ParallelMergeOptions.NotBuffered)
.Select((source, index) =>
{
Answer answer = null;
progress?.OnClassifying(source, index);
TFeatures features = selector(source, cancellationToken);
if (features != null)
{
try
{
answer = this.Classify(features, cancellationToken);
progress?.OnClassified(source, index, answer, null);
}
catch (Exception e)
{
progress?.OnClassified(source, index, null, e);
}
}
return answer;
}));
}
/// <summary>
/// Extracts features from a sequence of elements,
/// provides progress information,
/// and monitors cancellation requests.
/// </summary>
/// <typeparam name="T">The type of the elements to extract features from.</typeparam>
/// <param name="sources">The elements to extract the features from.</param>
/// <param name="selector">The selector that converts elements into <typeparamref name="TSource"/> objects.</param>
/// <param name="progress">The provider used to report a progress change. Can be <b>null</b>.</param>
/// <param name="cancellationToken">The cancellationToken token used to notify the classifier that the operation should be canceled.</param>
/// <returns>
/// The sequence of <typeparamref name="TFeatures"/> objects this method creates.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <para><paramref name="sources"/> is <b>null</b>.</para>
/// <para>-or-</para>
/// <para><paramref name="selector"/> is <b>null</b>.</para>
/// </exception>
public IEnumerable <TFeatures> BuildFeatures <T>(
IEnumerable <T> sources,
Func <T, CancellationToken, TSource> selector,
IClassifierProgress <T> progress,
CancellationToken cancellationToken)
{
if (sources == null)
{
throw new ArgumentNullException(nameof(sources));
}
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
return(sources
.AsParallel()
.AsOrdered()
.WithCancellation(cancellationToken)
.WithMergeOptions(ParallelMergeOptions.NotBuffered)
.Select((source, index) =>
{
progress?.OnClassifying(source, index);
TFeatures features = null;
try
{
features = this.BuildFeatures(selector(source, cancellationToken), cancellationToken);
progress?.OnClassified(source, index, null, null);
}
catch (Exception e)
{
progress?.OnClassified(source, index, null, e);
}
return features;
}));
}
