Entension methods for finding indices in a sequence, and finding the closest item in a sequence

ICD.Common.Utils.Tests/Extensions/EnumerableExtensionsTest.cs

@@ -123,6 +123,18 @@ namespace ICD.Common.Utils.Tests.Extensions
 			Assert.AreEqual(2, a.FindIndex(i => i == 3));
 		}
 
+		[Test]
+		public void FindIndicesPredicateTest()
+		{
+			IEnumerable<int> a = new[] {1, 2, 3, 4};
+
+			int[] indices = a.FindIndices(i => i % 2 == 0).ToArray();
+
+			Assert.AreEqual(2, indices.Length);
+			Assert.AreEqual(1, indices[0]);
+			Assert.AreEqual(3, indices[1]);
+		}
+
 		[Test]
 		public void SelectMultiTest()
 		{
@@ -144,7 +156,11 @@ namespace ICD.Common.Utils.Tests.Extensions
 			int[] values = {1, 2, 3};
 
 			int sum = 0;
-            IEnumerable<int> sequence = values.Select(v => { sum += v; return v; });
+			IEnumerable<int> sequence = values.Select(v =>
+			                                          {
+				                                          sum += v;
+				                                          return v;
+			                                          });
 
 			Assert.AreEqual(0, sum);
 			sequence.Execute();
@@ -350,6 +366,12 @@ namespace ICD.Common.Utils.Tests.Extensions
 			Assert.AreEqual(3, cPairs[1][1]);
 		}
 
+		[Test]
+		public void GetClosestTest()
+		{
+			Assert.AreEqual(20, new[] {10, 15, 20, 30, 35}.GetClosest(i => i - 21));
+		}
+
 		[Test]
 		public void MinByTest()
 		{

ICD.Common.Utils/Extensions/EnumerableExtensions.cs

@@ -226,6 +226,24 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="match"></param>
 		/// <returns></returns>
 		public static int FindIndex<T>(this IEnumerable<T> extends, Predicate<T> match)
+		{
+			if (extends == null)
+				throw new ArgumentNullException("extends");
+
+			if (match == null)
+				throw new ArgumentNullException("match");
+
+			return extends.FindIndices(match).FirstOrDefault(-1);
+		}
+
+		/// <summary>
+		/// Returns the indices that match the predicate.
+		/// </summary>
+		/// <typeparam name="T"></typeparam>
+		/// <param name="extends"></param>
+		/// <param name="match"></param>
+		/// <returns></returns>
+		public static IEnumerable<int> FindIndices<T>(this IEnumerable<T> extends, Predicate<T> match)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -238,11 +256,9 @@ namespace ICD.Common.Utils.Extensions
 			foreach (T item in extends)
 			{
 				if (match(item))
-					return index;
+					yield return index;
 				index++;
 			}
-
-			return -1;
 		}
 
 		/// <summary>
@@ -583,6 +599,18 @@ namespace ICD.Common.Utils.Extensions
 			}
 		}
 
+		/// <summary>
+		/// Gets the item from the sequence with the smallest calculated delta.
+		/// </summary>
+		/// <typeparam name="T"></typeparam>
+		/// <param name="extends"></param>
+		/// <param name="getDelta"></param>
+		/// <returns></returns>
+		public static T GetClosest<T>(this IEnumerable<T> extends, Func<T, int> getDelta)
+		{
+			return extends.MinBy(n => Math.Abs(getDelta(n)));
+		}
+
 		/// <summary>
 		/// Returns the minimal element of the given sequence, based on
 		/// the given projection.