Use stable_sort in PDFTane::CalculatePFDError

Use stable_sort instead of sort to avoid relying on
unspecified behaviour (wheter sort preserves order of equal elements)

src/core/algorithms/fd/tane/pfdtane.cpp

@@ -1,5 +1,7 @@
 #include "pfdtane.h"
 
+#include <algorithm>
+
 #include "config/error/option.h"
 #include "config/error_measure/option.h"
 #include "enums.h"
@@ -48,10 +50,10 @@ config::ErrorType PFDTane::CalculatePFDError(model::PositionListIndex const* x_p
     std::deque<Cluster> xa_index = xa_pli->GetIndex();
     std::shared_ptr<Cluster const> probing_table_ptr = x_pli->CalculateAndGetProbingTable();
     auto const& probing_table = *probing_table_ptr;
-    std::sort(xa_index.begin(), xa_index.end(),
-              [&probing_table](Cluster const& a, Cluster const& b) {
-                  return probing_table[a.front()] < probing_table[b.front()];
-              });
+    std::stable_sort(xa_index.begin(), xa_index.end(),
+                     [&probing_table](Cluster const& a, Cluster const& b) {
+                         return probing_table[a.front()] < probing_table[b.front()];
+                     });
     double sum = 0.0;
     std::size_t cluster_rows_count = 0;
     std::deque<Cluster> const& x_index = x_pli->GetIndex();

src/tests/test_pfdtane.cpp

@@ -65,9 +65,9 @@ INSTANTIATE_TEST_SUITE_P(
         PFDTaneTestMiningSuite, TestPFDTaneMining,
         ::testing::Values(
             PFDTaneMiningParams(44381, 0.3, +algos::PfdErrorMeasure::per_value, kTestFD),
-            PFDTaneMiningParams(39491, 0.1, +algos::PfdErrorMeasure::per_value, kIris),
+            PFDTaneMiningParams(19266, 0.1, +algos::PfdErrorMeasure::per_value, kIris),
             PFDTaneMiningParams(10695, 0.01, +algos::PfdErrorMeasure::per_value, kIris),
-            PFDTaneMiningParams(7893, 0.1, +algos::PfdErrorMeasure::per_value, kNeighbors10k),
+            PFDTaneMiningParams(44088, 0.1, +algos::PfdErrorMeasure::per_value, kNeighbors10k),
             PFDTaneMiningParams(41837, 0.01, +algos::PfdErrorMeasure::per_value, kNeighbors10k)
         ));