/// <summary>
/// Evaluates scored regression data.
/// </summary>
/// <param name="data">The data to evaluate.</param>
/// <param name="label">The name of the label column.</param>
/// <param name="groupId">The name of the groupId column.</param>
/// <param name="score">The name of the predicted score column.</param>
/// <returns>The evaluation metrics for these outputs.</returns>
public RankerMetrics Evaluate(IDataView data, string label, string groupId, string score)
{
Host.CheckValue(data, nameof(data));
Host.CheckNonEmpty(label, nameof(label));
Host.CheckNonEmpty(score, nameof(score));
var roles = new RoleMappedData(data, opt: false,
RoleMappedSchema.ColumnRole.Label.Bind(label),
RoleMappedSchema.ColumnRole.Group.Bind(groupId),
RoleMappedSchema.CreatePair(MetadataUtils.Const.ScoreValueKind.Score, score));
var resultDict = Evaluate(roles);
Host.Assert(resultDict.ContainsKey(MetricKinds.OverallMetrics));
var overall = resultDict[MetricKinds.OverallMetrics];
RankerMetrics result;
using (var cursor = overall.GetRowCursor(i => true))
{
var moved = cursor.MoveNext();
Host.Assert(moved);
result = new RankerMetrics(Host, cursor);
moved = cursor.MoveNext();
Host.Assert(!moved);
}
return(result);
}
private static RankerMetrics RankingDelta(
RankerMetrics a, RankerMetrics b)
{
var dcg = ComputeArrayDeltas(a.Dcg, b.Dcg);
var ndcg = ComputeArrayDeltas(a.Ndcg, b.Ndcg);
return(new RankerMetrics(dcg: dcg, ndcg: ndcg));
}
