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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "hamming_distance.h"
#include "temporary_vector_store.h"
#include <vespa/vespalib/util/binary_hamming_distance.h>
using vespalib::typify_invoke;
using vespalib::eval::TypifyCellType;
namespace search::tensor {
namespace {
struct CalcHamming {
template <typename LCT, typename RCT>
static double invoke(const vespalib::eval::TypedCells& lhs,
const vespalib::eval::TypedCells& rhs)
{
auto lhs_vector = lhs.unsafe_typify<LCT>();
auto rhs_vector = rhs.unsafe_typify<RCT>();
size_t sz = lhs_vector.size();
assert(sz == rhs_vector.size());
size_t sum = 0;
for (size_t i = 0; i < sz; ++i) {
sum += (lhs_vector[i] == rhs_vector[i]) ? 0 : 1;
}
return (double)sum;
}
};
}
using vespalib::eval::Int8Float;
template<typename FloatType>
class BoundHammingDistance : public BoundDistanceFunction {
private:
mutable TemporaryVectorStore<FloatType> _tmpSpace;
const vespalib::ConstArrayRef<FloatType> _lhs_vector;
public:
BoundHammingDistance(const vespalib::eval::TypedCells& lhs)
: _tmpSpace(lhs.size),
_lhs_vector(_tmpSpace.storeLhs(lhs))
{}
double calc(const vespalib::eval::TypedCells& rhs) const override {
size_t sz = _lhs_vector.size();
vespalib::ConstArrayRef<FloatType> rhs_vector = _tmpSpace.convertRhs(rhs);
assert(sz == rhs_vector.size());
auto a = _lhs_vector.data();
auto b = rhs_vector.data();
if constexpr (std::is_same<Int8Float, FloatType>::value) {
return (double) vespalib::binary_hamming_distance(a, b, sz);
} else {
size_t sum = 0;
for (size_t i = 0; i < sz; ++i) {
sum += (_lhs_vector[i] == rhs_vector[i]) ? 0 : 1;
}
return (double)sum;
}
}
double convert_threshold(double threshold) const override {
return threshold;
}
double to_rawscore(double distance) const override {
double score = 1.0 / (1.0 + distance);
return score;
}
double calc_with_limit(const vespalib::eval::TypedCells& rhs, double) const override {
// consider optimizing:
return calc(rhs);
}
};
template <typename FloatType>
BoundDistanceFunction::UP
HammingDistanceFunctionFactory<FloatType>::for_query_vector(const vespalib::eval::TypedCells& lhs) {
using DFT = BoundHammingDistance<FloatType>;
return std::make_unique<DFT>(lhs);
}
template <typename FloatType>
BoundDistanceFunction::UP
HammingDistanceFunctionFactory<FloatType>::for_insertion_vector(const vespalib::eval::TypedCells& lhs) {
using DFT = BoundHammingDistance<FloatType>;
return std::make_unique<DFT>(lhs);
}
template class HammingDistanceFunctionFactory<Int8Float>;
template class HammingDistanceFunctionFactory<float>;
template class HammingDistanceFunctionFactory<double>;
}
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