Compare two arrays and only get objects that are not part of the other one

PowerShell Help
1

Hi,

I currently have two arrays

array1
array2

I want to have all objects of array1 that are not part of array2

Im using this::
$array3 = $array1 | Where {$array2.ObjectID -NotContains $_.ObjectID}

This is almost working except for one issue:
This also adds objects of array2 that are not an object of array1 to array3, but this is NOT what i want. I want only to add objects of array 1 if they are not an object within array2

What am I doing wrong here?

BG
Gunnar

2

gugoeb,
Welcome to the forum. :wave:t4:

In PowerShell we work with objects and properties. To compare objects we use

For your requirement it would be something like this:

$Array1 = @'
ObjectID
1
2
3
4
5
'@ | 
ConvertFrom-Csv

$Array2 = @'
ObjectID
1
3
5
6
7
'@ | 
ConvertFrom-Csv

Compare-Object -ReferenceObject $Array1 -DifferenceObject $Array2 -Property ObjectID -PassThru | 
    Where-Object -Property SideIndicator -EQ -Value '<='

And BTW: When you post code please format it as code using the preformatted text button ( </> ). Simply place your curseor on an empty line, click the button and paste your code.

Thanks in advance

1 Like
3

The example you show would not do what you state. No members of $array2 will end up in $array3. Assuming the object has property ObjectID, it should do exactly what you desire.

$array1 = 1..4 | ForEach-Object {
    [PSCustomObject]@{
        ObjectID = $_
    }
}

$array2 = 3..6 | ForEach-Object {
    [PSCustomObject]@{
        ObjectID = $_
    }
}

$array3 = $array1 | Where {$array2.ObjectID -NotContains $_.ObjectID}

$array3

ObjectID
--------
       1
       2
2 Likes