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Adds weights to operations (1)...
Alexandre Leroux -
r1215:cb9ad4b9f97b
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1 #ifndef SCIQLOP_FUZZINGUTILS_H
1 #ifndef SCIQLOP_FUZZINGUTILS_H
2 #define SCIQLOP_FUZZINGUTILS_H
2 #define SCIQLOP_FUZZINGUTILS_H
3
3
4 #include <algorithm>
4 #include <random>
5 #include <random>
5
6
6 /**
7 /**
7 * Class that proposes random utility methods
8 * Class that proposes random utility methods
8 */
9 */
9 class RandomGenerator {
10 class RandomGenerator {
10 public:
11 public:
11 /// @return the unique instance of the random generator
12 /// @return the unique instance of the random generator
12 static RandomGenerator &instance();
13 static RandomGenerator &instance();
13
14
14 /// Generates a random double between [min, max]
15 /// Generates a random double between [min, max]
15 double generateDouble(double min, double max);
16 double generateDouble(double min, double max);
16 /// Generates a random int between [min, max]
17 /// Generates a random int between [min, max]
17 int generateInt(int min, int max);
18 int generateInt(int min, int max);
18
19
19 /// Returns a random element among the elements of a container. If the container is empty,
20 /**
20 /// returns an element built by default
21 * Returns a random element among the elements of a container. An item may be more likely to be
22 * selected if it has an associated weight greater than other items
23 * @param container the container from which to retrieve an element
24 * @param weights the weight associated to each element of the container. The vector must have
25 * the same size of the container for the weights to be effective
26 * @param nbDraws the number of random draws to perform
27 * @return the random element retrieved, an element built by default if the container is empty
28 */
21 template <typename T, typename ValueType = typename T::value_type>
29 template <typename T, typename ValueType = typename T::value_type>
22 ValueType randomChoice(const T &container);
30 ValueType randomChoice(const T &container, const std::vector<double> &weights = {});
23
31
24 private:
32 private:
25 std::mt19937 m_Mt;
33 std::mt19937 m_Mt;
26
34
27 explicit RandomGenerator();
35 explicit RandomGenerator();
28 };
36 };
29
37
30 template <typename T, typename ValueType>
38 template <typename T, typename ValueType>
31 ValueType RandomGenerator::randomChoice(const T &container)
39 ValueType RandomGenerator::randomChoice(const T &container, const std::vector<double> &weights)
32 {
40 {
33 if (container.empty()) {
41 if (container.empty()) {
34 return ValueType{};
42 return ValueType{};
35 }
43 }
36
44
37 auto randomIndex = generateInt(0, container.size() - 1);
45 // Generates weights for each element: if the weights passed in parameter are malformed (the
38 return container.at(randomIndex);
46 // number of weights defined is inconsistent with the number of elements in the container, or
47 // all weights are zero), default weights are used
48 auto nbIndexes = container.size();
49 std::vector<double> indexWeights(nbIndexes);
50 if (weights.size() != nbIndexes || std::all_of(weights.cbegin(), weights.cend(),
51 [](const auto &val) { return val == 0.; })) {
52 std::fill(indexWeights.begin(), indexWeights.end(), 1.);
53 }
54 else {
55 std::copy(weights.begin(), weights.end(), indexWeights.begin());
56 }
57
58 // Performs a draw to determine the index to return
59 std::discrete_distribution<> d{indexWeights.cbegin(), indexWeights.cend()};
60 return container.at(d(m_Mt));
39 }
61 }
40
62
41 #endif // SCIQLOP_FUZZINGUTILS
63 #endif // SCIQLOP_FUZZINGUTILS
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