Merge pull request #486 from amlalejini/fix-random-reset-seed

Fix emp::Random ResetSeed

Author: amlalejini

include/emp/math/Random.hpp

@@ -85,6 +85,10 @@ namespace emp {
 
       weyl_state *= 2;  // Make sure starting state is even.
 
+      // Reset other internal state
+      value = 0;
+      expRV = 0.0;
+
       Get(); // Prime the new sequence by skipping the first number.
     }
 

tests/math/Random.cpp

@@ -71,7 +71,7 @@ TEST_CASE("Test Random", "[math]")
   REQUIRE(b2_result < 50);
 
   emp::RandomStdAdaptor randomStd(rnd);
-  REQUIRE(randomStd(4) == 1);
+  REQUIRE(randomStd(4) == 3);
 
   REQUIRE(rnd.GetRandGeometric(1) == 1);
   REQUIRE(rnd.GetRandGeometric(0) == std::numeric_limits<uint32_t>::infinity());
@@ -295,3 +295,48 @@ TEST_CASE("Another Test random", "[math]")
     REQUIRE(v.first + v.second == 0);
   }
 }
+
+TEST_CASE("Calling ResetSeed should reset all generator internal state", "[math]") {
+
+  SECTION("Test internal 'value'") {
+    // Get Seed
+    emp::Random rnd(-1); // Initialize without a seed
+    rnd.ResetSeed(5);
+    REQUIRE(rnd.GetSeed() == 5);
+
+    emp::vector<int> sequence_a;
+    for (size_t i = 0; i < 10; ++i) {
+      sequence_a.emplace_back(rnd.GetInt(10000));
+    }
+
+    rnd.ResetSeed(5);
+    emp::vector<int> sequence_b;
+    for (size_t i = 0; i < 10; ++i) {
+      sequence_b.emplace_back(rnd.GetInt(10000));
+    }
+
+    // Tests internal 'value'
+    REQUIRE(sequence_a == sequence_b);
+  }
+
+  SECTION("Test internal expV") {
+    emp::Random rnd(10);
+    rnd.GetRandNormal(); // Adjusts expV with time-based seed generator
+
+    rnd.ResetSeed(4); // Should reset expV
+    emp::vector<double> norm_seq_a;
+    for (size_t i = 0; i < 1000; ++i) {
+      norm_seq_a.emplace_back(rnd.GetRandNormal());
+    }
+
+    rnd.ResetSeed(4);
+    emp::vector<double> norm_seq_b;
+    for (size_t i = 0; i < 1000; ++i) {
+      norm_seq_b.emplace_back(rnd.GetRandNormal());
+    }
+
+    // Tests internal expV
+    REQUIRE(norm_seq_a == norm_seq_b);
+  }
+
+}