improve multcomp_pmt

Author: qddyy

inst/include/pmt/impl_multcomp_pmt.hpp

@@ -5,23 +5,31 @@ RObject impl_multcomp_pmt(
     const NumericVector data,
     IntegerVector group,
     T&& statistic_func,
-    const double n_permu)
+    const double n_permu
+)
 {
     Stat<progress> statistic_container;
 
-    int k = *(group.end() - 1);
+    int k = *std::prev(group.end());
 
     auto statistic_closure = statistic_func(data, group);
-    auto multcomp_update = [&statistic_container, &statistic_closure, data, group, k]() {
-        auto pairwise_closure = statistic_closure(data, group);
-
-        for (int i = 1; i < k - 1; i++) {
+    auto multcomp_update = [&statistic_container, &statistic_closure, data, group, pairs = [k]() {
+        std::vector<std::pair<int, int>> pairs;
+        pairs.reserve(C(k, 2));
+        for (int i = 1; i < k; i++) {
             for (int j = i + 1; j <= k; j++) {
-                statistic_container << pairwise_closure(i, j);
+                pairs.emplace_back(i, j);
             }
         }
+        return pairs;
+    }()]() {
+        auto pairwise_closure = statistic_closure(data, group);
 
-        return statistic_container << pairwise_closure(k - 1, k);
+        auto it = pairs.begin();
+        do {
+            statistic_container << pairwise_closure(it->first, it->second);
+        } while (++it != std::prev(pairs.end()));
+        return statistic_container << pairwise_closure(it->first, it->second);
     };
 
     statistic_container.allocate(C(k, 2), n_permu != 0 ? n_permu : n_permutation(group));