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April 3, 2021 01:59
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Sort a struct of arrays using an extra array as indexer (therefore, with one level of indirection)
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#include <algorithm> | |
#include <array> | |
#include <iostream> | |
#include <random> | |
#include <string_view> | |
const int LEN = 10; | |
using Indexer = int; | |
class SOA | |
{ | |
public: | |
std::array<int, LEN> propA; | |
std::array<int, LEN> propB; | |
std::array<int, LEN> propC; | |
std::array<int, LEN> propD; | |
std::array<Indexer, LEN> indexIndirct; | |
explicit SOA() | |
{ | |
for (int i = 0; i < LEN; i++) | |
propA[i] = propB[i] = propC[i] = propD[i] = indexIndirct[Indexer(i)] = i; | |
print("Init\t"); | |
} | |
auto shuffle(std::mt19937& gen) -> void | |
{ | |
std::ranges::shuffle(propA, gen); | |
std::ranges::shuffle(propB, gen); | |
std::ranges::shuffle(propC, gen); | |
std::ranges::shuffle(propD, gen); | |
std::ranges::shuffle(indexIndirct, gen); | |
print("Shuffle\t"); | |
} | |
auto sortByA() -> void | |
{ | |
auto cmp = [this](const Indexer& a, const Indexer& b) { | |
return propA[a] < propA[b]; | |
}; | |
std::sort(indexIndirct.begin(), indexIndirct.end(), cmp); | |
} | |
auto sortByB() -> void | |
{ | |
auto cmp = [this](const Indexer& a, const Indexer& b) { | |
return propB[a] < propB[b]; | |
}; | |
std::sort(indexIndirct.begin(), indexIndirct.end(), cmp); | |
} | |
auto print(std::string_view sv) -> void | |
{ | |
std::cout << sv << '\t'; | |
print(); | |
} | |
auto print() -> void | |
{ | |
std::cout << "A: ["; | |
for (int i = 0; i < LEN; i++) | |
std::cout << propA[indexIndirct[i]] << ", "; | |
std::cout << "\b\b], B: ["; | |
for (int i = 0; i < LEN; i++) | |
std::cout << propB[indexIndirct[i]] << ", "; | |
std::cout << "\b\b]\n"; | |
} | |
}; | |
SOA soa; | |
int | |
main() | |
{ | |
std::random_device rd; | |
std::mt19937 gen{ rd() }; | |
soa.shuffle(gen); | |
soa.sortByA(); | |
soa.print("Sort By A"); | |
soa.sortByB(); | |
soa.print("Sort By B"); | |
} | |
///OUTPUT///////////////////////////////////////////////////////////////////////////////// | |
// Init A: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9], B: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] // | |
// Shuffle A: [1, 4, 2, 3, 5, 8, 0, 9, 6, 7], B: [6, 8, 0, 9, 5, 4, 1, 2, 3, 7] // | |
// Sort By A A: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9], B: [1, 6, 0, 9, 8, 5, 3, 7, 4, 2] // | |
// Sort By B A: [2, 0, 9, 6, 8, 5, 1, 7, 4, 3], B: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] // | |
////////////////////////////////////////////////////////////////////////////////////////// |
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