mirror of
https://github.com/ceres-solver/ceres-solver.git
synced 2026-08-29 16:40:38 +08:00
Sameer Agarwal
39b7cbaa5d
This reduces pre-processor time when finding an
ordering automatically substantially.
Before:
ComputeStableSchurOrdering
Delta Cumulative
CreateHessianGraph : 0.50324 0.50324
Preordering : 0.00692 0.51017
StableIndependentSet : 0.26341 0.77358
ConstantParameterBlocks : 0.00095 0.77453
Total : 0.23978 1.01431
After:
ComputeStableSchurOrdering
Delta Cumulative
CreateHessianGraph : 0.17183 0.17183
Preordering : 0.00226 0.17409
StableIndependentSet : 0.12510 0.29919
ConstantParameterBlocks : 0.00073 0.29991
Total : 0.01638 0.31629
Change-Id: I50bbac69f8b3f19240a61a218913cebf34da0db5
94 lines
3.4 KiB
C++
94 lines
3.4 KiB
C++
// Ceres Solver - A fast non-linear least squares minimizer
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// Copyright 2023 Google Inc. All rights reserved.
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// http://ceres-solver.org/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of Google Inc. nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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// Author: sameeragarwal@google.com (Sameer Agarwal)
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#include "ceres/single_linkage_clustering.h"
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#include "absl/container/flat_hash_map.h"
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#include "absl/container/flat_hash_set.h"
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#include "absl/log/check.h"
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#include "ceres/graph.h"
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#include "ceres/graph_algorithms.h"
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namespace ceres::internal {
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int ComputeSingleLinkageClustering(
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const SingleLinkageClusteringOptions& options,
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const WeightedGraph<int>& graph,
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absl::flat_hash_map<int, int>* membership) {
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CHECK(membership != nullptr);
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membership->clear();
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// Initially each vertex is in its own cluster.
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const absl::flat_hash_set<int>& vertices = graph.vertices();
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for (const int v : vertices) {
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(*membership)[v] = v;
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}
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for (const int vertex1 : vertices) {
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const absl::flat_hash_set<int>& neighbors = graph.Neighbors(vertex1);
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for (const int vertex2 : neighbors) {
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// Since the graph is undirected, only pay attention to one side
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// of the edge and ignore weak edges.
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if ((vertex1 > vertex2) ||
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(graph.EdgeWeight(vertex1, vertex2) < options.min_similarity)) {
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continue;
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}
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// Use a union-find algorithm to keep track of the clusters.
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const int c1 = FindConnectedComponent(vertex1, membership);
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const int c2 = FindConnectedComponent(vertex2, membership);
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if (c1 == c2) {
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continue;
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}
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if (c1 < c2) {
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(*membership)[c2] = c1;
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} else {
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(*membership)[c1] = c2;
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}
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}
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}
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// Make sure that every vertex is connected directly to the vertex
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// identifying the cluster.
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int num_clusters = 0;
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for (auto& m : *membership) {
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m.second = FindConnectedComponent(m.first, membership);
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if (m.first == m.second) {
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++num_clusters;
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}
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}
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return num_clusters;
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}
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} // namespace ceres::internal
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