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/*
* SparseAccumulator.hpp
*
* Created on: 14.05.2014
* Author: Michael Wegner (michael.wegner@student.kit.edu)
*/
#ifndef NETWORKIT_ALGEBRAIC_SPARSE_ACCUMULATOR_HPP_
#define NETWORKIT_ALGEBRAIC_SPARSE_ACCUMULATOR_HPP_
#include <algorithm>
#include <cassert>
#include <vector>
#include <networkit/Globals.hpp>
namespace NetworKit {
class SparseAccumulator final {
private:
count row;
std::vector<double> values; // w
std::vector<count> occupied; // b
std::vector<index> indices; // LS
public:
SparseAccumulator(count size) : row(1), values(size), occupied(size, 0) {}
void scatter(double value, index pos) {
if (occupied[pos] < row) {
values[pos] = value;
occupied[pos] = row;
indices.push_back(pos);
} else {
values[pos] += value;
}
}
template <typename L>
void scatter(double value, index pos, L &handle) {
assert(pos < values.size());
if (occupied[pos] < row) {
values[pos] = value;
occupied[pos] = row;
indices.push_back(pos);
} else {
values[pos] = handle(values[pos], value);
}
}
template <typename L>
count gather(L handle) {
count nonZeros = 0;
std::sort(indices.begin(), indices.end());
for (index idx : indices) {
handle(row - 1, idx, values[idx]);
++nonZeros;
}
return nonZeros;
}
void increaseRow() {
++row;
indices.clear();
}
};
} /* namespace NetworKit */
#endif // NETWORKIT_ALGEBRAIC_SPARSE_ACCUMULATOR_HPP_