C#中的时间跨度总和 [英] Sum of TimeSpans in C#

问题描述

我有一个包含 TimeSpan 变量的对象集合:

MyObject{时间跨度持续时间{得到；放;}}

我想用 LINQ 来总结这些时间.当然，(从 MyCollection 中的 r 选择 r.TheDuration).Sum();不起作用！

我正在考虑将 TheDuration 的数据类型更改为 int，然后将其求和并将总和转换为 TimeSpan.这会很混乱，因为我收藏中的每个 TheDuration 都被用作其他地方的时间跨度.

对这个总结有什么建议吗?

解决方案

不幸的是，没有接受 IEnumerable 的 Sum 重载.此外，目前还没有为类型参数指定基于运算符的泛型约束的方法，因此即使 TimeSpan 是本机"可求和的，但泛型代码无法轻松获取这一事实.

一种选择是，如您所说，总结一个等效于时间跨度的整数类型，然后再次将 那个 和转换为 TimeSpan.对此的理想属性是 TimeSpan.Ticks，准确地往返.但是根本没有必要更改类的属性类型；你可以项目:

var totalSpan = new TimeSpan(myCollection.Sum(r => r.TheDuration.Ticks));

或者，如果您想坚持使用 TimeSpan 的 + 运算符进行求和，则可以使用 Aggregate 运算符:

var totalSpan = myCollection.Aggregate(时间跨度.零，(sumSoFar, nextMyObject) =>sumSoFar + nextMyObject.TheDuration);

I have a collection of objects that include a TimeSpan variable:

MyObject
{ 
    TimeSpan TheDuration { get; set; }
}

I want to use LINQ to sum those times. Of course, (from r in MyCollection select r.TheDuration).Sum(); doesn't work!

I'm thinking of changing the datatype of TheDuration to an int and then summing it and converting the sum to a TimeSpan. That will be messy because each TheDuration in my collection is used in as a timespan somewhere else.

Any suggestion on this summation?

解决方案

Unfortunately, there isn't a an overload of Sum that accepts an IEnumerable<TimeSpan>. Additionally, there's no current way of specifying operator-based generic constraints for type-parameters, so even though TimeSpan is "natively" summable, that fact can't be picked up easily by generic code.

One option would be to, as you say, sum up an integral-type equivalent to the timespan instead, and then turn that sum into a TimeSpan again. The ideal property for this is TimeSpan.Ticks, which round-trips accurately. But it's not necessary to change the property-type on your class at all; you can just project:

var totalSpan = new TimeSpan(myCollection.Sum(r => r.TheDuration.Ticks));

Alternatively, if you want to stick to the TimeSpan's + operator to do the summing, you can use the Aggregate operator:

var totalSpan = myCollection.Aggregate
                (TimeSpan.Zero, 
                (sumSoFar, nextMyObject) => sumSoFar + nextMyObject.TheDuration);

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