Compares group membership of 2 or more users

Compare-ADGroupMembership.ps1

Function Compare-ADGroupMembership {
    [CmdletBinding()]
    Param (
        [Parameter(Mandatory=$true,ValueFromPipeline=$true)]
        [Alias('Name')]
        [string[]]$Username
    )

    BEGIN {
        $groups = @{}
    }
    PROCESS {
        ForEach ($u in $Username) {
            $membership = Get-ADPrincipalGroupMembership -Identity $u
            foreach ($g in $membership) {
                Write-Verbose "Group: $($g.name)"
                if (!$groups.ContainsKey($g.name)) {
                    $groups.Add($g.name,[System.Collections.ArrayList]@()) | Out-Null
                }
                $groups[$g.name].Add($u) | Out-Null
            }
        }
    }
    END {
        ForEach($g in $groups.GetEnumerator()) {
            $o = New-Object -TypeName PSObject
            $o | Add-Member NoteProperty GroupName $g.Name
            ForEach($u in $Username) {
                $o | Add-Member NoteProperty $u (@{$true=$u;$false=''}[$g.Value -contains $u])
            }
            Write-Output $o
        }
    }
}