Sorensen–Dice coefficient: Difference between revisions
Added C++ solution
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If there is a built-in or easily, freely available library implementation for Sørensen–Dice coefficient calculations it is acceptable to use that with a pointer to where it may be obtained.
=={{header|C++}}==
{{trans|Wren}}
<syntaxhighlight lang="cpp">#include <algorithm>
#include <cctype>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <iterator>
#include <set>
#include <sstream>
#include <string>
#include <vector>
std::multiset<std::string> split(const std::string& phrase) {
std::multiset<std::string> result;
std::istringstream is(phrase);
std::string word;
while (is >> word) {
for (char& ch : word) {
ch = std::tolower(static_cast<unsigned char>(ch));
}
size_t length = word.size();
if (length == 1) {
result.emplace(1, word[0]);
} else {
for (size_t i = 0; i + 1 < length; ++i) {
result.insert(std::string{word[i], word[i + 1]});
}
}
}
return result;
}
double sorensen(const std::string& s1, const std::string& s2) {
auto a = split(s1);
auto b = split(s2);
std::multiset<std::string> c;
std::set_intersection(a.begin(), a.end(), b.begin(), b.end(),
std::inserter(c, c.begin()));
return (2.0 * c.size()) / (a.size() + b.size());
}
int main() {
std::vector<std::string> tasks;
std::ifstream is("tasks.txt");
if (!is) {
std::cerr << "Cannot open tasks file.\n";
return EXIT_FAILURE;
}
std::string task;
while (getline(is, task)) {
tasks.push_back(task);
}
const size_t tc = tasks.size();
const std::string tests[] = {"Primordial primes",
"Sunkist-Giuliani formula",
"Sieve of Euripides", "Chowder numbers"};
std::vector<std::pair<double, size_t>> sdi(tc);
std::cout << std::fixed;
for (const std::string& test : tests) {
for (size_t i = 0; i != tc; ++i) {
sdi[i] = std::make_pair(sorensen(tasks[i], test), i);
}
std::partial_sort(sdi.begin(), sdi.begin() + 5, sdi.end(),
[](const std::pair<double, size_t>& a,
const std::pair<double, size_t>& b) {
return a.first > b.first;
});
std::cout << test << " >\n";
for (size_t i = 0; i < 5 && i < tc; ++i) {
std::cout << " " << sdi[i].first << ' ' << tasks[sdi[i].second]
<< '\n';
}
std::cout << '\n';
}
return EXIT_SUCCESS;
}</syntaxhighlight>
{{out}}
<pre>
Primordial primes >
0.685714 Sequence of primorial primes
0.666667 Factorial primes
0.571429 Primorial numbers
0.545455 Prime words
0.521739 Almost prime
Sunkist-Giuliani formula >
0.565217 Almkvist-Giullera formula for pi
0.378378 Faulhaber's formula
0.342857 Haversine formula
0.333333 Check Machin-like formulas
0.307692 Resistance calculator
Sieve of Euripides >
0.461538 Four sides of square
0.461538 Sieve of Pritchard
0.413793 Sieve of Eratosthenes
0.400000 Piprimes
0.384615 Sierpinski curve
Chowder numbers >
0.782609 Chowla numbers
0.640000 Powerful numbers
0.608696 Rhonda numbers
0.608696 Fermat numbers
0.600000 Lah numbers
</pre>
=={{header|J}}==
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