Remove Duplicates within an array element in Powershell

Question

How can I remove duplicate values within an array element in PowerShell?

For example:

$array[0] = C1 C1 C3 C3
$array[1] = C1 C1 C2 C2

How can I removed the duplicates in Powershell, so that I have:

$array[0] = C1 C3
$array[1] = C1 C2

I tried $array[0] | Select -Unique but it was not successful. Nothing changed. With $array | Select - Unique the duplicates are removed without considering the single array elements.

Anyone a good idea?

You should comma separate array elements when creating your array. — AdminOfThings, May 04 '21 at 16:20
How is this array created? Are `C1 C1 C3 C3` different property values or is it a `string`? — Santiago Squarzon, May 04 '21 at 16:22
@SantiagoSquarzon It is a String. It gets these values from an excel file — TheCodingKing, May 04 '21 at 16:23
@AdminOfThings Also if I comma seperate it, how can I remove duplicates in one array element? — TheCodingKing, May 04 '21 at 16:25
If they are space separated elements in a string, then you can use `$array[0] -split ' ' | select -unique`. — AdminOfThings, May 04 '21 at 16:26
You need a delimiter so you can convert each `string` into a `string[]`, I think this is what @AdminOfThings mean,then is easy to get unique values. — Santiago Squarzon, May 04 '21 at 16:27
Exactly, agreed. You could in theory use `$array[0] -split '\s+' | select -Unique` but you would be removing **all** extra spaces and some elements of your `string` might have spaces... If that makes sense. — Santiago Squarzon, May 04 '21 at 16:28
@SantiagoSquarzon actually they are seperated by \n, but I will try it and write back if it worked — TheCodingKing, May 04 '21 at 16:31
@AdminOfThings beat me to it first. That;s exactly what i would do and what i was gonna suggest. To "*update*" the array after you can assign it to the same index: `$array[0] = $array[0].Split(' ') | Select-Object -Unique` — Abraham Zinala, May 04 '21 at 16:36

score 2 · Accepted Answer · answered May 04 '21 at 16:44

2

This works perfect if you use spaces as delimiter however if your string should have had a space then it will be removed. Ideally, you could create your $array with a specific delimiter like | or ; or , that's up to you.

$array=@(
    'C1 C1 C3 C3'
    'C1 C1 C2 C2'
    'C1 C2 C3 C4'
    'C1 C1 C2 C2'
    'C1 C2 C3 C3'
    'C1 C2 C2 C2'
)

for($i=0;$i -lt $array.Count;$i++)
{
    $array[$i] = ($array[$i] -split '\s+' | Select-Object -Unique) -join ' '
}

PS /> $array
C1 C3
C1 C2
C1 C2 C3 C4
C1 C2
C1 C2 C3
C1 C2

answered May 04 '21 at 16:44

Santiago Squarzon

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Thank yo, +1 from me, I was adding/removing LogonWorkstations in AD, the following splits them by comma, removes duplicates, and re-joins. `$LogonWorkstations = ($LogonWorkstations -split ',' | Select-Object -Unique) -join ','` – Aubs Jul 19 '23 at 14:19

Remove Duplicates within an array element in Powershell

1 Answers1