Fix inverted accept/reject counts when swapping operator tuning

src/main/java/coupledMCMC/CoupledMCMC.java

@@ -774,24 +774,24 @@ void swapOperatorTuning(HeatedChain mcmc1, HeatedChain mcmc2) {
 
 
 		for (int i = 0; i < operatorList1.size(); i++){
-			Operator operator1 = operatorList1.get(i);
-			Operator operator2 = operatorList2.get(i);
-
-		    int m_nNrRejected = operator1.get_m_nNrRejected();
-		    int m_nNrAccepted = operator1.get_m_nNrAccepted();
-		    int m_nNrRejectedForCorrection = operator1.get_m_nNrRejectedForCorrection();
-		    int m_nNrAcceptedForCorrection = operator1.get_m_nNrAcceptedForCorrection();
-
-		    operator1.setAcceptedRejected(operator2.get_m_nNrRejected(), operator2.get_m_nNrAccepted(), operator2.get_m_nNrRejectedForCorrection(), operator2.get_m_nNrAcceptedForCorrection());
-		    operator2.setAcceptedRejected(m_nNrAccepted, m_nNrRejected, m_nNrAcceptedForCorrection, m_nNrRejectedForCorrection);
-
-
-		    double coercableParameterValue = operator1.getCoercableParameterValue();
-		    operator1.setCoercableParameterValue(operator2.getCoercableParameterValue());
-		    operator2.setCoercableParameterValue(coercableParameterValue);
-
+			swapTuning(operatorList1.get(i), operatorList2.get(i));
 		}		
 	}
+
+	// operators tune themselves from their acceptance rate, so the counts must travel with the tuned value
+	static void swapTuning(Operator operator1, Operator operator2) {
+		int accepted = operator1.get_m_nNrAccepted();
+		int rejected = operator1.get_m_nNrRejected();
+		int acceptedForCorrection = operator1.get_m_nNrAcceptedForCorrection();
+		int rejectedForCorrection = operator1.get_m_nNrRejectedForCorrection();
+		operator1.setAcceptedRejected(operator2.get_m_nNrAccepted(), operator2.get_m_nNrRejected(),
+				operator2.get_m_nNrAcceptedForCorrection(), operator2.get_m_nNrRejectedForCorrection());
+		operator2.setAcceptedRejected(accepted, rejected, acceptedForCorrection, rejectedForCorrection);
+
+		double coercableParameterValue = operator1.getCoercableParameterValue();
+		operator1.setCoercableParameterValue(operator2.getCoercableParameterValue());
+		operator2.setCoercableParameterValue(coercableParameterValue);
+	}
 
 	/* makes the schedule of when to swap which chains */
 	@SuppressWarnings("unchecked")

src/test/java/coupledMCMC/SwapOperatorTuningTest.java

@@ -0,0 +1,49 @@
+package coupledMCMC;
+
+import beast.base.spec.domain.Real;
+import beast.base.spec.inference.operator.RealRandomWalkOperator;
+import beast.base.spec.inference.parameter.RealScalarParam;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class SwapOperatorTuningTest {
+
+    private static RealRandomWalkOperator operator(double windowSize) {
+        RealScalarParam<Real> x = new RealScalarParam<>(0.0, Real.INSTANCE);
+        RealRandomWalkOperator op = new RealRandomWalkOperator();
+        op.initByName("scalar", x, "windowSize", windowSize, "weight", 1.0);
+        return op;
+    }
+
+    private static List<Integer> counts(RealRandomWalkOperator op) {
+        return List.of(op.get_m_nNrAccepted(), op.get_m_nNrRejected(),
+                op.get_m_nNrAcceptedForCorrection(), op.get_m_nNrRejectedForCorrection());
+    }
+
+    @Test
+    void swapTuningExchangesAcceptAndRejectCountsWithoutMixingThemUp() {
+        RealRandomWalkOperator a = operator(1.0);
+        RealRandomWalkOperator b = operator(2.0);
+        a.setAcceptedRejected(3, 7, 2, 6);
+        b.setAcceptedRejected(5, 1, 4, 0);
+
+        CoupledMCMC.swapTuning(a, b);
+
+        assertEquals(List.of(5, 1, 4, 0), counts(a));
+        assertEquals(List.of(3, 7, 2, 6), counts(b));
+    }
+
+    @Test
+    void swapTuningExchangesTheTunedParameterToo() {
+        RealRandomWalkOperator a = operator(1.0);
+        RealRandomWalkOperator b = operator(2.0);
+
+        CoupledMCMC.swapTuning(a, b);
+
+        assertEquals(2.0, a.getCoercableParameterValue());
+        assertEquals(1.0, b.getCoercableParameterValue());
+    }
+}