Functions/Get-Intersection.ps1
|
function Get-Intersection { <# .SYNOPSIS Get the intersection of two sets. .DESCRIPTION In mathematics, the intersection A ∩ B of two sets A and B is the set that contains all elements of A that also belong to B, but no other elements. .EXAMPLE Get-Intersection (1,10,2,1) (1,2,3) .EXAMPLE Get-Intersection 'John' 'Ronny' .EXAMPLE Get-Intersection 'Jon' 'jon' -CaseSensitive .LINK https://en.wikipedia.org/wiki/Intersection_(set_theory) https://communary.wordpress.com/ https://github.com/gravejester/Communary.PASM .INPUTS System.Array System.String .NOTES Author: Øyvind Kallstad Date: 14.02.2016 Version: 1.0 Dependencies: Get-TypeName #> [OutputType([System.Array])] [CmdletBinding()] param ( [Parameter(Position = 0, Mandatory = $true)] $Set1, [Parameter(Position = 1, Mandatory = $true)] $Set2, # Makes string intersection case sensitive. [Parameter()] [switch] $CaseSensitive ) try { # if sets are strings, convert to array of chars if ($Set1 -is [string]) { if (-not($CaseSensitive)) { $Set1 = $Set1.ToLowerInvariant() } $Set1 = $Set1.ToCharArray() } if ($Set2 -is [string]) { if (-not($CaseSensitive)) { $Set2 = $Set2.ToLowerInvariant() } $Set2 = $Set2.ToCharArray() } # check that the sets are arrays if (-not($set1.GetType().IsArray) -or -not($Set2.GetType().IsArray)) { Write-Warning 'Oops! Input must be arrays!' break } # get the types of the elements in the sets $arrayTypesSet1 = Get-TypeName $Set1 $arrayTypesSet2 = Get-TypeName $Set2 # check that the sets do not contain mixed types if (($arrayTypesSet1 -is [array]) -and ($arrayTypesSet2 -is [array])) { Write-Warning 'Oops! One, or both, of the sets contain mixed types!' break } # check that the sets contain the same type if ($arrayTypesSet1 -ne $arrayTypesSet2) { Write-Warning 'Oops! The two sets contain different types!' break } # create hash sets $hashSet1 = New-Object System.Collections.Generic.HashSet[$arrayTypesSet1] (,($set1 -as "$arrayTypesSet1[]")) $hashSet2 = New-Object System.Collections.Generic.HashSet[$arrayTypesSet2] (,($set2 -as "$arrayTypesSet2[]")) # get the union between them $hashSet1.IntersectWith($hashSet2) # convert hashset to array and write output to pipeline $outputArray = New-Object -TypeName "$arrayTypesSet1[]" ($hashSet1.Count) $hashSet1.CopyTo($outputArray) Write-Output $outputArray } catch { Write-Warning $_.Exception.Message } } |