C# equivalent of Python’s list slicing (list[:])

While porting some Python code, I wanted to make it as close of a match as possible so I came up with this extension method.

Enjoy.

 1: /// <summary>Slices the specified collection like Python does</summary>
 2: /// <typeparam name="T"></typeparam>
 3: /// <param name="me">the collection</param>
 4: /// <param name="start">The start point.</param>
 5: /// <param name="end">The end point.</param>
 6: /// <returns></returns>
 7: /// <exception cref="System.ArgumentException">starting point must be less than or equal to ending point;start</exception>
 8: /// <example>
 9: /// <code>
10: /// var numbers=new[]{1,2,3,4,5};
11: /// var eg = numbers.Slice(-3,-1);
12: /// foreach (var i in eg)
13: /// {
14: ///     Console.Write("{0}, ", i);
15: /// }
16: /// Console.Writeline();
17: ///
18: /// // Output: 3, 4,
19: /// </code>
20: /// </example>
21: public static IEnumerable<T> Slice<T>(this IEnumerable<T> me, int? start = null, int? end = null)
22: {
23:     if (start.HasValue && end.HasValue && start.Value > end.Value)
24:     {
25:         throw new ArgumentException("starting point must be less than or equal to ending point", "start");
26:     }
27:
28:     if (start.HasValue && start < 0)
29:     {
30:         start = me.Count() + start;
31:     }
32:     if (end.HasValue && end < 0)
33:     {
34:         end = me.Count() + end;
35:     }
36:
37:     if (!start.HasValue)
38:     {
39:         start = 0;
40:     }
41:
42:     if (!end.HasValue)
43:     {
44:         end = me.Count();
45:     }
46:
47:     return me.Skip(start.Value).Take(end.Value - start.Value);
48: }

MSTest:

 1: [TestMethod]
 2: public void TestSlicing()
 3: {
 4:     var numbers = new[] { 0, 1, 2, 3, 4, 5, 6, 7 };
 5:     var sliced = numbers.Slice(-3, -1);
 6:     Assert.AreEqual(2, sliced.Count());
 7:     Assert.AreEqual(5, sliced.ElementAt(0));
 8:     Assert.AreEqual(6, sliced.ElementAt(1));
 9:
10:     sliced = numbers.Slice(1, 4);
11:     Assert.AreEqual(3, sliced.Count());
12:     Assert.AreEqual(1, sliced.ElementAt(0));
13:     Assert.AreEqual(2, sliced.ElementAt(1));
14:     Assert.AreEqual(3, sliced.ElementAt(2));
15: }