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Fixed issue where number of extra "augmentation" edges asked for are larger than the number of remaining edges after taking out the spanning tree.

release/4.3a0
Frank Dellaert 2019-04-06 22:56:20 -04:00
parent 18d26d12af
commit 798e730d87
1 changed files with 14 additions and 7 deletions
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21
gtsam/linear/SubgraphPreconditioner.cpp
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@ -397,23 +397,30 @@ Subgraph::shared_ptr SubgraphBuilder::operator() (const GaussianFactorGraph &gfg
const SubgraphBuilderParameters &p = parameters_;
const Ordering inverse_ordering = Ordering::Natural(gfg);
const FastMap<Key, size_t> forward_ordering = inverse_ordering.invert();
const size_t n = inverse_ordering.size(), t = n * p.complexity_ ;
const size_t n = inverse_ordering.size(), m = gfg.size();
vector<double> w = weights(gfg);
const vector<size_t> tree = buildTree(gfg, forward_ordering, w);
// Make sure the subgraph preconditioner does not include more than half of
// the edges beyond the spanning tree, or we might as well solve the whole thing.
size_t numExtraEdges = n * p.complexity_;
const size_t numRemaining = m - (n - 1);
numExtraEdges = std::min(numExtraEdges, numRemaining/2);
/* sanity check */
// Calculate weights
vector<double> weights = this->weights(gfg);
// Build spanning tree.
const vector<size_t> tree = buildTree(gfg, forward_ordering, weights);
if ( tree.size() != n-1 ) {
throw std::runtime_error("SubgraphBuilder::operator() tree.size() != n-1 failed ");
}
/* down weight the tree edges to zero */
// Downweight the tree edges to zero.
for ( const size_t id: tree ) {
w[id] = 0.0;
weights[id] = 0.0;
}
/* decide how many edges to augment */
vector<size_t> offTree = sample(w, t);
vector<size_t> offTree = sample(weights, numExtraEdges);
vector<size_t> subgraph = unary(gfg);
subgraph.insert(subgraph.end(), tree.begin(), tree.end());