LINQ从列表中选择项目并从原始列表中保存它们的索引[重复]

Question

我从列表中选择了项目。我如何也从原始列表中保存他们的索引？

var originalList = new List<int>(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 });
var selectedItems = originalList.Where(e => e > 5); // 6, 7, 8, 9, 10, 11, 12, 13

一个例子：

选定项目：

• (6, 索引 = 5)
• (7, 索引 = 6)
• (8, 索引 = 7)
• 等等...

Answer 1

您必须记住索引。可以通过Select重载实现

var selectedItems = originalList
   .Select((e, index) => new { e, index })
   .Where(p => p.e > 5)
   .ToList();

Answer 2

是的，可能

var originalList = new List<int>(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 });
var selectedItems = originalList.Select((e, i) => (e, i))
                                .Where(x => x.e > 5)
                                .Select(x => $"({x.e} , index = {x.i})") ;