PowerShell中的并集和交集?

问题描述

我有一个具有以下结构的对象数组:

I have an array of objects of the following structure:

structure Disk
{
  int UID;
  String Computer;
}

一台计算机可能有一堆共享磁盘，一个磁盘可能在计算机之间共享.

A computer may have a bunch of shared disks, and a disk may be shared among computers.

我想找出所有计算机共有的所有磁盘.例如，我有计算机 A、B 和 C；磁盘 1、2 和 3.磁盘阵列为{1,A}、{1,B}、{2,A}、{2,B}、{2,C}、{3,A}.我想要的结果应该是磁盘2，因为它出现在A、B和C上.

I want to find out all the disks common to all the computers. For example, I have computer A, B, and C; Disks 1, 2, and 3.The disk array is {1,A}, {1,B}, {2,A},{2,B},{2,C},{3,A}.The result that I want should be the disk 2, because it appears on A, B, and C.

有没有有效的方法来实现这一目标?

Is there a effective way to achieve this?

使用多个 foreach 循环是可以实现的，但我绝对想要一个更好的方法.我正在考虑像交集这样的操作，但在 PowerShell 中没有找到.

With multiple foreach loops it's achievable, but definitely I want a better way. I'm thinking about operations like intersection, but didn't find this in PowerShell.

推荐答案

假设 $arr 是数组，你可以这样做:

Assuming $arr is the array, you can do like this:

$computers = $arr | select -expand computer -unique
$arr | group uid | ?{$_.count -eq $computers.count} | select name

一般来说，我会像这样在 Powershell 中处理联合和交集:

---

In general, I would approach union and intersection in Powershell like this:

$a = (1,2,3,4)
$b = (1,3,4,5)
$a + $b | select -uniq    #union
$a | ?{$b -contains $_}   #intersection

但是对于您所问的问题，上述解决方案运行良好，并且与术语标准定义中的并集和交集无关.

But for what you are asking, the above solution works well and not really about union and intersection in the standard definition of the terms.

更新:

我已经编写了 pslinq，它提供了 Union-List 和 Intersect-List，有助于实现与 Powershell 的集合并集和交集.

I have written pslinq which provides Union-List and Intersect-List that help to achieve set union and intersection with Powershell.

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