LINQ MAX()与空值 [英] LINQ Max() with Nulls
问题描述
我有一个包含了一堆点(用X和Y分量)的列表。
I have a list that contains a bunch of Points (with an X and Y component).
我想获得最大x对于列表中的所有点,像这样的:
I want to get the Max X for all points in the list, like this:
double max = pointList.Max(p=> p.X);
问题是,当我在列表中,而不是一个点一个空。什么将是解决这个问题的最好办法。
The problem is when I have a null in the list instead of a point. What would be the best way to get around this issue?
推荐答案
好了,你可以只筛选出来:
Well, you could just filter them out:
pointList.Where(p => p != null).Max(p => p.X)
在另一方面,如果你想空
s到被视为尽管他们被分有X坐标 0
(或类似),你可以这样做:
On the other hand, if you want null
s to be treated as though they were points having X-coordinate 0
(or similar), you could do:
pointList.Max(p => p == null ? 0 : p.X)
待办事项注意,如果序列为空,这两种方法都将抛出。这其中的一个解决方法(如果需要的话)将是:
Do note that both techniques will throw if the sequence is empty. One workaround for this (if desirable) would be:
pointList.DefaultIfEmpty().Max(p => p == null ? 0 : p.X)
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