Fixed Equals and GetHashCode method for MatchedFragmentIon

mzLib/Omics/Fragmentation/MatchedFragmentIon.cs

@@ -72,19 +72,32 @@ public override string ToString()
             return NeutralTheoreticalProduct.ProductType + "" + NeutralTheoreticalProduct.FragmentNumber + "+" + Charge + "\t;" + NeutralTheoreticalProduct.NeutralMass;
         }
 
+        // Doubles are accurate to within 15-17 significant digits. Rounding to 10 decimal places ensures accurate comparison up to 100,000 m/z (non-inclusive)
+        internal const int MzDecimalDigits = 10;
+        // Rounding to 6 decimal places ensures accurate comparison up to 1,000,000,000 AU (non-inclusive)
+        internal const int IntensityDecimalDigits = 6;
+
         public override bool Equals(object obj)
         {
-            MatchedFragmentIon other = (MatchedFragmentIon)obj;
+            return obj is MatchedFragmentIon otherIon && this.Equals(otherIon);
+        }
 
+
+        public bool Equals(MatchedFragmentIon other)
+        {
             return this.NeutralTheoreticalProduct.Equals(other.NeutralTheoreticalProduct)
                 && this.Charge == other.Charge
-                && Math.Abs(Mz - other.Mz) < 0.0001
-                && Math.Abs(Intensity - other.Intensity) < 0.0001;
+                && Math.Round(Mz, MzDecimalDigits) - Math.Round(other.Mz, MzDecimalDigits) == 0
+                && Math.Round(Intensity, IntensityDecimalDigits) - Math.Round(other.Intensity, IntensityDecimalDigits) == 0;
         }
 
         public override int GetHashCode()
         {
-            return Mz.GetHashCode();
+            return HashCode.Combine(
+                NeutralTheoreticalProduct.GetHashCode(),
+                Charge.GetHashCode(),
+                Math.Round(Mz, MzDecimalDigits).GetHashCode(),
+                Math.Round(Intensity, IntensityDecimalDigits).GetHashCode());
         }
     }
 }

mzLib/Test/TestFragments.cs

@@ -883,16 +883,19 @@ public static void Test_ProductMonoisotopicMass()
         public static void Test_MatchedFragmentGetHashCode()
         {
             Product P = new Product(ProductType.b, FragmentationTerminus.N, 1, 1, 1, 0);
+            Product pPrime = new Product(ProductType.b, FragmentationTerminus.N, 1, 1, 1, 0);
             MatchedFragmentIon m = new MatchedFragmentIon(P, 1, 1, 1);
-            Assert.AreEqual(1072693248, m.GetHashCode());
+            MatchedFragmentIon mPrime = new MatchedFragmentIon(pPrime, 1, 1, 1);
+            Assert.AreEqual(P.GetHashCode(), pPrime.GetHashCode());
+            Assert.AreEqual(mPrime.GetHashCode(), m.GetHashCode());
         }
 
         [Test]
         public static void TestMatchedFragmentIonEquals()
         {
             Product P = new Product(ProductType.b, FragmentationTerminus.N, 1, 1, 1, 0);
-            MatchedFragmentIon ion1 = new MatchedFragmentIon(P, experMz: 150, experIntensity: 99.99999, charge: 2);
-            MatchedFragmentIon ion2 = new MatchedFragmentIon(P, experMz: 149.99999, experIntensity: 100, charge: 2);
+            MatchedFragmentIon ion1 = new MatchedFragmentIon(P, experMz: 150, experIntensity: 99.99999999999, charge: 2);
+            MatchedFragmentIon ion2 = new MatchedFragmentIon(P, experMz: 149.99999999999, experIntensity: 100, charge: 2);
             Assert.AreEqual(ion1, ion2);
         }