ENH: Replace std::array<float, N> with Eigen

vis/include/combo_iterator.hpp

@@ -1,98 +1,30 @@
 #pragma once
 
-#include <vector>
-#include <array>
+#include <set>
 #include <algorithm>
-#include <numeric>
-#include <stdexcept>
 
-size_t choose(size_t n, size_t k) {
-    if (k == 0) return 1;
-    return n * choose(n - 1, k - 1) / k;
+template<typename V, typename M>
+V select(const V &data, const M &mask, size_t count) {
+    V result;
+    result.reserve(count);
+
+    for (int i = 0; i < mask.size(); ++i) {
+        if (mask[i]) result.push_back(data[i]);
+    }
+
+    return result;
 }
 
-template<class T>
-class ComboIterator {
-private:
-    const std::vector<T> &options;
+template<typename V>
+std::vector<V> combinations(const V &data, const size_t count) {
+    std::vector<V> result;
 
-    std::vector<bool> bits;
-    std::vector<T> curr;
-    int at;
+    std::vector<bool> mask(data.size(), false);
+    std::fill(mask.begin(), mask.begin() + count, true);
 
-    void set_curr() {
-        for (int i = 0, j = 0; i < bits.size(); ++i) {
-            if (bits[i]) curr[j++] = options[i];
-        }
-    }
+    do {
+        result.push_back(select(data, mask, count));
+    } while (std::next_permutation(mask.begin(), mask.end(), std::greater<>()));
 
-public:
-    ComboIterator(const std::vector<T> &options, int k, int at = 0)
-        : options(options), bits(options.size()), curr(k), at(at) {
-        std::fill(bits.begin(), bits.begin() + k, true);
-        set_curr();
-    }
-
-    [[nodiscard]] bool operator==(const ComboIterator<T> &o) const {
-        return at == o.at;
-    }
-
-    [[nodiscard]] bool operator!=(const ComboIterator<T> &o) const {
-        return at != o.at;
-    }
-
-    auto operator*() const {
-        return curr;
-    }
-
-    const auto &operator->() const {
-        return &this;
-    }
-
-    auto operator++(int) {
-        std::prev_permutation(bits.begin(), bits.end());
-        set_curr();
-        ++at;
-        return *this;
-    }
-
-    auto operator++() &{
-        auto res = *this;
-        (*this)++;
-        return res;
-    }
-
-    auto operator--(int) {
-        std::next_permutation(bits.begin(), bits.end());
-        set_curr();
-        --at;
-        return *this;
-    }
-
-    auto operator--() &{
-        auto res = *this;
-        (*this)--;
-        return res;
-    }
-};
-
-template<class T>
-class Combos {
-private:
-    const std::vector<T> options;
-    int k;
-    int size;
-
-public:
-    Combos(const std::vector<T> &options, size_t k)
-        : options(options), k(k), size(choose(options.size(), k)) {
-    }
-
-    ComboIterator<T> begin() const {
-        return ComboIterator<T>(options, k);
-    }
-
-    ComboIterator<T> end() const {
-        return ComboIterator<T>(options, k, size);
-    }
-};
+    return result;
+}