mirror of
https://github.com/ceres-solver/ceres-solver.git
synced 2026-08-29 16:40:38 +08:00
Sameer Agarwal
29c21f5680
SparseCholesky is an interface to sparse cholesky factorization routines across sparse linear algebra libraries. Each sparse linear algebra library is responsible for implementing its own instance of this interface. As a result the various places - SparseNormalCholeskySolver, SparseSchurComplementSolver and VisibilityBasedPreconditioner are significantly simplified. Change-Id: I8b465705eae83bba9e1adfffcc741a05c70faf2e
104 lines
3.6 KiB
C++
104 lines
3.6 KiB
C++
// Ceres Solver - A fast non-linear least squares minimizer
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// Copyright 2015 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 "ceres/graph.h"
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#include "ceres/collections_port.h"
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#include "ceres/graph_algorithms.h"
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namespace ceres {
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namespace 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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HashMap<int, int>* membership) {
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CHECK_NOTNULL(membership)->clear();
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// Initially each vertex is in its own cluster.
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const HashSet<int>& vertices = graph.vertices();
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for (HashSet<int>::const_iterator it = vertices.begin();
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it != vertices.end();
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++it) {
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(*membership)[*it] = *it;
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}
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for (HashSet<int>::const_iterator it1 = vertices.begin();
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it1 != vertices.end();
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++it1) {
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const int vertex1 = *it1;
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const HashSet<int>& neighbors = graph.Neighbors(vertex1);
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for (HashSet<int>::const_iterator it2 = neighbors.begin();
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it2 != neighbors.end();
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++it2) {
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const int vertex2 = *it2;
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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 (HashMap<int, int>::iterator it = membership->begin();
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it != membership->end();
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++it) {
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it->second = FindConnectedComponent(it->first, membership);
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if (it->first == it->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 internal
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} // namespace ceres
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