Begin Stratified KFold

src/Platform/CMakeLists.txt

@@ -4,4 +4,5 @@ include_directories(${BayesNet_SOURCE_DIR}/lib/Files)
 include_directories(${BayesNet_SOURCE_DIR}/lib/mdlp)
 include_directories(${BayesNet_SOURCE_DIR}/lib/argparse/include)
 add_executable(main Experiment.cc Folding.cc platformUtils.cc)
+add_executable(testx testx.cpp Folding.cc)
 target_link_libraries(main BayesNet ArffFiles mdlp "${TORCH_LIBRARIES}")

src/Platform/Folding.cc

@@ -1,21 +1,23 @@
 #include "Folding.h"
 #include <algorithm>
+#include <map>
 #include <random>
 
 using namespace std;
 
-KFold::KFold(int k, int n, int seed)
+KFold::KFold(int k, int n, int seed) : k(k), n(n), seed(seed)
 {
-    this->k = k;
-    this->n = n;
     indices = vector<int>(n);
     iota(begin(indices), end(indices), 0); // fill with 0, 1, ..., n - 1
-    shuffle(indices.begin(), indices.end(), default_random_engine(seed));
+    random_device rd;
+    default_random_engine random_seed(seed == -1 ? rd() : seed);
+    shuffle(indices.begin(), indices.end(), random_seed);
 }
 pair<vector<int>, vector<int>> KFold::getFold(int nFold)
 {
+
     if (nFold >= k || nFold < 0) {
-        throw invalid_argument("nFold (" + to_string(nFold) + ") must be less than k (" + to_string(k) + ")");
+        throw out_of_range("nFold (" + to_string(nFold) + ") must be less than k (" + to_string(k) + ")");
     }
     int nTest = n / k;
     auto train = vector<int>();
@@ -28,4 +30,60 @@ pair<vector<int>, vector<int>> KFold::getFold(int nFold)
         }
     }
     return { train, test };
+}
+StratifiedKFold::StratifiedKFold(int k, const vector<int>& y, int seed) :
+    k(k), seed(seed)
+{
+    // n = y.size();
+    // map<int, vector<int>> class_to_indices;
+    // for (int i = 0; i < n; ++i) {
+    //     class_to_indices[y[i]].push_back(i);
+    // }
+    // random_device rd;
+    // default_random_engine random_seed(seed == -1 ? rd() : seed);
+    // for (auto& [cls, indices] : class_to_indices) {
+    //     shuffle(indices.begin(), indices.end(), random_seed);
+    //     int fold_size = n / k;
+    //     for (int i = 0; i < k; ++i) {
+    //         int start = i * fold_size;
+    //         int end = (i == k - 1) ? indices.size() : (i + 1) * fold_size;
+    //         stratified_indices.emplace_back(indices.begin() + start, indices.begin() + end);
+    //     }
+    // }
+    n = y.size();
+    stratified_indices.resize(k);
+    vector<int> class_counts(*max_element(y.begin(), y.end()) + 1, 0);
+    for (auto i = 0; i < n; ++i) {
+        class_counts[y[i]]++;
+    }
+    vector<int> class_starts(class_counts.size());
+    partial_sum(class_counts.begin(), class_counts.end() - 1, class_starts.begin() + 1);
+    vector<int> indices(n);
+    for (auto i = 0; i < n; ++i) {
+        int label = y[i];
+        stratified_indices[class_starts[label]] = i;
+        class_starts[label]++;
+    }
+    int fold_size = n / k;
+    int remainder = n % k;
+    int start = 0;
+    for (auto i = 0; i < k; ++i) {
+        int fold_length = fold_size + (i < remainder ? 1 : 0);
+        stratified_indices[i].resize(fold_length);
+        copy(indices.begin() + start, indices.begin() + start + fold_length, stratified_indices[i].begin());
+        start += fold_length;
+    }
+}
+pair<vector<int>, vector<int>> StratifiedKFold::getFold(int nFold)
+{
+    if (nFold >= k || nFold < 0) {
+        throw out_of_range("nFold (" + to_string(nFold) + ") must be less than k (" + to_string(k) + ")");
+    }
+    vector<int> test_indices = stratified_indices[nFold];
+    vector<int> train_indices;
+    for (int i = 0; i < k; ++i) {
+        if (i == nFold) continue;
+        train_indices.insert(train_indices.end(), stratified_indices[i].begin(), stratified_indices[i].end());
+    }
+    return { train_indices, test_indices };
 }

src/Platform/Folding.h

@@ -7,12 +7,19 @@ private:
     int k;
     int n;
     vector<int> indices;
-
+    int seed;
 public:
-    KFold(int k, int n, int seed);
-    pair<vector<int>, vector<int>> getFold(int);
+    KFold(int k, int n, int seed = -1);
+    pair<vector<int>, vector<int>> getFold(int nFold);
 };
-class KStratifiedFold {
-
+class StratifiedKFold {
+private:
+    int k;
+    int n;
+    vector<vector<int>> stratified_indices;
+    unsigned seed;
+public:
+    StratifiedKFold(int k, const vector<int>& y, int seed = -1);
+    pair<vector<int>, vector<int>> getFold(int nFold);
 };
 #endif

src/Platform/main.cpp

@@ -1,51 +0,0 @@
-#include "Folding.h"
-#include <iostream>
-using namespace std;
-class A {
-private:
-	int a;
-public:
-	A(int a) : a(a) {}
-	int getA() { return a; }
-};
-class B : public A {
-private:
-	int b;
-public:
-	B(int a, int b) : A(a), b(b) {}
-	int getB() { return b; }
-};
-class C : public A {
-private:
-	int c;
-public:
-	C(int a, int c) : A(a), c(c) {}
-	int getC() { return c; }
-};
-int main()
-{
-	auto fold = KFold(5, 100, 1);
-	for (int i = 0; i < 5; ++i) {
-		cout << "Fold: " << i << endl;
-		auto [train, test] = fold.getFold(i);
-		cout << "Train: ";
-		cout << "(" << train.size() << "): ";
-		for (auto j = 0; j < static_cast<int>(train.size()); j++)
-			cout << train[j] << ", ";
-		cout << endl;
-		cout << "Test: ";
-		cout << "(" << train.size() << "): ";
-		for (auto j = 0; j < static_cast<int>(test.size()); j++)
-			cout << test[j] << ", ";
-		cout << endl;
-		cout << "Vector poly" << endl;
-		auto some = vector<A>();
-		auto cx = C(5, 4);
-		auto bx = B(7, 6);
-		some.push_back(cx);
-		some.push_back(bx);
-		for (auto& obj : some) {
-			cout << "Obj :" << obj.getA() << endl;
-		}
-	}
-}

src/Platform/testx.cpp

@@ -0,0 +1,74 @@
+#include "Folding.h"
+#include <map>
+#include <iostream>
+using namespace std;
+class A {
+private:
+	int a;
+public:
+	A(int a) : a(a) {}
+	int getA() { return a; }
+};
+class B : public A {
+private:
+	int b;
+public:
+	B(int a, int b) : A(a), b(b) {}
+	int getB() { return b; }
+};
+class C : public A {
+private:
+	int c;
+public:
+	C(int a, int c) : A(a), c(c) {}
+	int getC() { return c; }
+};
+string counts(vector<int> y, vector<int> indices)
+{
+	auto result = map<int, int>();
+	for (auto i = 0; i < indices.size(); ++i) {
+		result[y[indices[i]]]++;
+	}
+	string final_result = "";
+	for (auto i = 0; i < result.size(); ++i)
+		final_result += to_string(i) + " -> " + to_string(result[i]) + " // ";
+	final_result += "\n";
+	return final_result;
+}
+
+int main()
+{
+	auto y = vector<int>(150);
+	fill(y.begin(), y.begin() + 50, 0);
+	fill(y.begin() + 50, y.begin() + 100, 1);
+	fill(y.begin() + 100, y.end(), 2);
+	//auto fold = KFold(5, 150);
+	auto fold = StratifiedKFold(5, y, 0);
+	for (int i = 0; i < 5; ++i) {
+		cout << "Fold: " << i << endl;
+		auto [train, test] = fold.getFold(i);
+		cout << "Train: ";
+		cout << "(" << train.size() << "): ";
+		for (auto j = 0; j < static_cast<int>(train.size()); j++)
+			cout << train[j] << ", ";
+		cout << endl;
+		cout << "Train Statistics : " << counts(y, train);
+		cout << "-------------------------------------------------------------------------------" << endl;
+		cout << "Test: ";
+		cout << "(" << test.size() << "): ";
+		for (auto j = 0; j < static_cast<int>(test.size()); j++)
+			cout << test[j] << ", ";
+		cout << endl;
+		cout << "Test Statistics: " << counts(y, test);
+		cout << "==============================================================================" << endl;
+		// cout << "Vector poly" << endl;
+		// auto some = vector<A>();
+		// auto cx = C(5, 4);
+		// auto bx = B(7, 6);
+		// some.push_back(cx);
+		// some.push_back(bx);
+		// for (auto& obj : some) {
+		// 	cout << "Obj :" << obj.getA() << endl;
+		// }
+	}
+}