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One document and the score that ranked it.

public sealed record SearchHit(int Document, double Score)

Parameters — Document is the row index in the matrix that was scored. Score is higher-is- better, on the scale of whatever produced it.

Example — the shape both Bm25Index.Top and RankFusion.Rrf return.

using Lodestar.Text.Search;

IReadOnlyList<SearchHit> fused = RankFusion.Rrf([[2, 0, 1], [0, 1, 2]]);

int best = fused[0].Document;  // => 0
int howMany = fused.Count;  // => 3

Remarks — Document is an index, not an identifier: it means a row of the matrix that was scored, and mapping it back to a document of your own is the caller's job.

The two producers put different things in Score. BM25's is unbounded and can be negative; RRF's is a sum of reciprocals in (0, rankings × 1/(k+1)]. Neither is comparable with the other, which is exactly why fusing them goes through ranks rather than through scores.

Applies to — net10.0, netstandard2.0.

See also — Bm25Index.Top, RankFusion.