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Make key generation more efficient

release/4.3a0
Frank Dellaert 2024-09-23 18:36:00 -07:00
parent ae8d79cb3c
commit 74c40556e3
1 changed files with 14 additions and 16 deletions
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30
gtsam/discrete/DecisionTreeFactor.cpp
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@ -147,14 +147,14 @@ namespace gtsam {
size_t i; size_t i;
ADT result(*this); ADT result(*this);
for (i = 0; i < nrFrontals; i++) { for (i = 0; i < nrFrontals; i++) {
Key j = keys()[i]; Key j = keys_[i];
result = result.combine(j, cardinality(j), op); result = result.combine(j, cardinality(j), op);
} }
// create new factor, note we start keys after nrFrontals // Create new factor, note we start with keys after nrFrontals:
DiscreteKeys dkeys; DiscreteKeys dkeys;
for (; i < keys().size(); i++) { for (; i < keys_.size(); i++) {
Key j = keys()[i]; Key j = keys_[i];
dkeys.push_back(DiscreteKey(j, cardinality(j))); dkeys.push_back(DiscreteKey(j, cardinality(j)));
} }
return std::make_shared<DecisionTreeFactor>(dkeys, result); return std::make_shared<DecisionTreeFactor>(dkeys, result);
@ -179,24 +179,22 @@ namespace gtsam {
result = result.combine(j, cardinality(j), op); result = result.combine(j, cardinality(j), op);
} }
// create new factor, note we collect keys that are not in frontalKeys
/* /*
Due to branch merging, the labels in `result` may be missing some keys Create new factor, note we collect keys that are not in frontalKeys.
Due to branch merging, the labels in `result` may be missing some keys.
E.g. After branch merging, we may get a ADT like: E.g. After branch merging, we may get a ADT like:
Leaf [2] 1.0204082 Leaf [2] 1.0204082
This is missing the key values used for branching. Hence, code below traverses the original keys and omits those in
frontalKeys. We loop over cardinalities, which is O(n) even for a map, and
then "contains" is a binary search on a small vector.
*/ */
KeyVector difference, frontalKeys_(frontalKeys), keys_(keys());
// Get the difference of the frontalKeys and the factor keys using set_difference
std::sort(keys_.begin(), keys_.end());
std::sort(frontalKeys_.begin(), frontalKeys_.end());
std::set_difference(keys_.begin(), keys_.end(), frontalKeys_.begin(),
frontalKeys_.end(), back_inserter(difference));
DiscreteKeys dkeys; DiscreteKeys dkeys;
for (Key key : difference) { for (auto&& [key, cardinality] : cardinalities_) {
dkeys.push_back(DiscreteKey(key, cardinality(key))); if (!frontalKeys.contains(key)) {
dkeys.push_back(DiscreteKey(key, cardinality));
}
} }
return std::make_shared<DecisionTreeFactor>(dkeys, result); return std::make_shared<DecisionTreeFactor>(dkeys, result);
} }