Finding duplicates in an array

Question

The following code results in an Array:

[Array]$Object = [PSCustomObject]@{
    P1 = 'Appel'
    P2 = 'Cherry'
    P3 = 'Appel'
    P4 = 'Banana'    
}
$Object += [PSCustomObject]@{
    P1 = 'Good'
    P2 = 'Bad'
    P3 = 'Good'
    P4 = 'Good'
}
$Object += [PSCustomObject]@{
    P1 = 'Green'
    P2 = 'Red'
    P3 = 'Green'
    P4 = 'Yellow'
}
$Object

This generates:

P1         P2         P3       P4                          
--         --         --       --                          
Appel      Cherry     Appel    Banana                      
Good       Bad        Good     Good                        
Green      Red        Green    Yellow

I'm trying to figure out how I can have it report the duplicates, in this case the desired outcome would be P1 and P3 as they both have the same info in them:

P1      P3                       
--      --                       
Appel   Appel                    
Good    Good                     
Green   Green

Because the values are not in the same object it's not as simple as using Group-Object to retrieve them. Any help would be appreciated.

Something along the lines of if (!(Compare-Object $object.p1 $object.p3)) { echo duplicate }? — arco444
– arco444, Commented Dec 7, 2015 at 12:34
Yes arco444, that's what I'm playing with now.Compare-Object $Object.P1 $Object.P3 -IncludeEqual -ExcludeDifferent. I only need to figure out how to loop through the collection to have it compare everything. — DarkLite1
– DarkLite1, Commented Dec 7, 2015 at 12:35

Mathias R. Jessen · Accepted Answer · 2015-12-07 11:43:38Z

6

You could use Group-Object to find duplicate property values in each object by inspecting the value of each entry in the psobject.Properties property:

PS C:\> $Object |ForEach-Object {
    $_.psobject.Properties | Group-Object { $_.Value } | Format-Table
}

Count Name                      Group
----- ----                      -----
    2 Appel                     {string P1=Appel, string P3=Appel}
    1 Cherry                    {string P2=Cherry}
    1 Banana                    {string P4=Banana}


Count Name                      Group
----- ----                      -----
    3 Good                      {string P1=Good, string P3=Good, string P4=Good}
    1 Bad                       {string P2=Bad}


Count Name                      Group
----- ----                      -----
    2 Green                     {string P1=Green, string P3=Green}
    1 Red                       {string P2=Red}
    1 Yellow                    {string P4=Yellow}

answered Dec 7, 2015 at 11:43

Mathias R. Jessen

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5 Comments

DarkLite1 Over a year ago

Thank you Mathias for putting me on the right track, but I really need to compare all 3 values to see if they all 3 match..

Mathias R. Jessen Over a year ago

I'm still not entirely sure what you trying to accomplish here. None of the 3 objects in your $Object array have duplicates between them

DarkLite1 Over a year ago

You are correct, the values are not in the same object. I've updated the OP to be more clear.

Mathias R. Jessen Over a year ago

Yes, but what about the P4 property then? It has a duplicate value in the second object

DarkLite1 Over a year ago

I don't care about that, it only interests me if all 3 property values are equal.

DarkLite1 · Accepted Answer · 2015-12-07 13:36:15Z

4

Finally figured it out:

$Props = $Object | Get-Member | ? MemberType -EQ NoteProperty | Measure-Object | Select-Object -ExpandProperty Count

$Result = for ($a = 1; $a -le $Props; $a++) {
    for ($b = 1; $b -le $Props; $b++) {
        if ($a -ne $b) {
            if (($R = Compare-Object ([String[]]$Object.("P$a")) ([String[]]$Object.("P$b")) -IncludeEqual -ExcludeDifferent).Count -eq 3) {
                $R.InputObject | Out-String
            }
        }
    }
}

$Result | Select-Object -Unique

edited Dec 7, 2015 at 13:36

answered Dec 7, 2015 at 13:22

DarkLite1

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