获取与我的linq匹配的行的索引
我有一个linq语句,我想知道是否有可能获得与我的陈述相符的行的标记? 这里是:
var result = list3.Where(middle => list4.Any(x => x == middle.Middle.category1)).Select(obj => new { obj, dt = DateTime.ParseExact(obj.LeftColumn, dateFormat, CultureInfo.InvariantCulture) }) .Where(x => x.dt >= datetimepickerChoice1 && x.dt x.obj).ToList();
您可以使用Select
(或Where
)的重载,它也会调用元素的索引:
var result = list3.Select((middle, index) => new{ middle, index }) .Where(x => list4.Any(xx => xx == x.middle.Middle.category1)) .Select(x => new { x.middle, x.index, dt = DateTime.ParseExact(x.middle.LeftColumn, dateFormat, CultureInfo.InvariantCulture) }) .Where(x => x.dt >= czas11 && x.dt <= czas22) .Select(x => x.index) .ToList();
附注:考虑将变量名更改为更有意义。 这是不可读的。
你的意思是?
var result = list3.Where(middle => list4.Any(x => x == middle.Middle.category1)) .Select(obj => new { obj, dt = DateTime.ParseExact(obj.LeftColumn, dateFormat, CultureInfo.InvariantCulture) }) .Where(x => x.dt >= czas11 && x.dt <= czas22) .Select((x,index) =>new{ x.obj,Index=index}).ToList();
另请注意,如果要经常搜索与谓词匹配的项的指示,则可能值得编写一个非常简单的扩展方法:
public static class IEnumerableExt { public static IEnumerable FindIndices(this IEnumerable self, Predicate predicate) { int i = 0; foreach (var element in self) { if (predicate(element)) yield return i; ++i; } } }
您可以这样称呼:
var result = list3.FindIndices(x => list4.Any(xx => xx == x.middle.Middle.category1));