75 lines
2.4 KiB
C++
75 lines
2.4 KiB
C++
/*
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* Copyright (C) 2026 Emeric Poupon
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*
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* This file is part of LMS.
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*
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* LMS is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* LMS is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with LMS. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "SameArtistConstraint.hpp"
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#include <algorithm>
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#include "TrackCandidateContext.hpp"
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namespace lms::recommendation
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{
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namespace
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{
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bool hasCommonArtist(const std::vector<db::ArtistId>& a, const std::vector<db::ArtistId>& b)
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{
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// Both vectors are sorted
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auto ia{ a.cbegin() }, ib{ b.cbegin() };
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while (ia != a.cend() && ib != b.cend())
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{
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if (*ia == *ib)
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return true;
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if (*ia < *ib)
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++ia;
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else
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++ib;
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}
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return false;
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}
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} // namespace
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SameArtistConstraint::SameArtistConstraint(const TrackMetadataMap& trackMetadata, std::size_t window)
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: _trackMetadata{ trackMetadata }
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, _window{ window }
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{
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}
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SameArtistConstraint::~SameArtistConstraint() = default;
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float SameArtistConstraint::computeScore(const TrackCandidateContext& context) const
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{
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const auto it{ _trackMetadata.find(context.candidateTrackId) };
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if (it == _trackMetadata.cend() || it->second.artistIds.empty())
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return {};
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const auto& candidateArtists{ it->second.artistIds };
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float score{};
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const auto& selected{ context.selectedTracks };
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for (std::size_t i{ 1 }; i <= _window && i <= selected.size(); ++i)
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{
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const auto sit{ _trackMetadata.find(selected[selected.size() - i]) };
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if (sit != _trackMetadata.cend() && hasCommonArtist(candidateArtists, sit->second.artistIds))
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score += 1.F / static_cast<float>(i);
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}
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return score;
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}
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} // namespace lms::recommendation
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