PowerShell copy an array completely

Question

I'm trying to create a complete copy of an existing array. Every time I try this it doesn't seem to work. The thing is that I'm modifying the object names inside the new copied array, but they're also changed in the original array..

Simplified example

Function Get-Fruits {
    Param (
        $Fruits = @('Banana', 'Apple', 'Pear')
    )
    foreach ($F in $Fruits) {
        [PSCustomObject]@{
            Type = $F
        }
    }
}

$FruitsOriginal = Get-Fruits

Function Rename-ObjectName {
    # Copy the array here
    $FruitsNew = $FruitsOriginal # Not a true copy
    $FruitsNew = $FruitsOriginal | % {$_} # Not a true copy
    $FruitsNew = $FruitsOriginal.Clone() # Not a true copy

    $FruitsNew | Get-Member | ? MemberType -EQ NoteProperty | % {
    
        $Name = $_.Name

        $FruitsNew | % {
            $_ | Add-Member 'Tasty fruits' -NotePropertyValue $_.$Name
            $_.PSObject.Properties.Remove($Name)
        }
    }
}

Rename-ObjectName

The desired result is 2 completely separate arrays.

$FruitsOriginal

Type
----
Banana
Apple
Pear

$FruitsNew

Tasty fruits
------------
Banana
Apple
Pear

Thank you for your help.

Hey DarkLite... when was the last time you had a tasty fresh peer? — Matt
– Matt, Commented Apr 17, 2015 at 13:20
'The string's the thing' from the Scripting Guys and fruits in my case make it easier to demonstrate code, lol. But I'm more of a Banana fan if I have to be honest. Hope you get elected, I voted for you :) — DarkLite1
– DarkLite1, Commented Apr 17, 2015 at 13:24
You might have me confused with someone else as I am not in the running (or am I?). Also I was trying to point out that peer was spelled wrong — Matt
– Matt, Commented Apr 17, 2015 at 13:27
Always so serious ;) Fixed it, thx! You are correct, voted for the wrong Matt. In any case, I always appreciate your help, so a special thank you 2 u. — DarkLite1
– DarkLite1, Commented Apr 17, 2015 at 13:30
Possible duplicate of Powershell - Copying an array of reference types as value types instead — jpaugh
– jpaugh, Commented Dec 20, 2016 at 14:35

Todd Mitchell · Accepted Answer · 2017-04-24 18:43:23Z

26

# Copy the array here
$FruitsCopy = @()
$FruitsCopy = $FruitsCopy + $FruitsOriginal

answered Apr 24, 2017 at 18:43

Todd Mitchell

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3 Comments

Zout Over a year ago

$FruitsCopy = @() + $FruitsOriginal works too

BobCormorano Over a year ago

It did not work for me, but I realise why: my array is an array of objects. This comment from David Berg explains it perfectly.

Simon Elms Jan 13 at 7:10

This is still a shallow copy. The result is the same as using $FruitsOriginal.Clone(), as far as I can see.

Alex · Accepted Answer · 2015-04-17 12:24:03Z

15

You can use serialisation to deep clone your array:

#Original data
$FruitsOriginal = Get-Fruits

# Serialize and Deserialize data using BinaryFormatter
$ms = New-Object System.IO.MemoryStream
$bf = New-Object System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
$bf.Serialize($ms, $FruitsOriginal)
$ms.Position = 0

#Deep copied data
$FruitsNew = $bf.Deserialize($ms)
$ms.Close()

answered Apr 17, 2015 at 12:24

Alex

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3 Comments

DarkLite1 Over a year ago

Fully awesome! Thank you very much Jaco :)

Frank Lesniak Over a year ago

Is there an object "depth" limit to this approach? Also, worth noting that the above only works if $FruitsOriginal.GetType().IsSerializable -eq $true

Frank Lesniak Over a year ago

Sorry, one more thing: if $FruitsOriginal contains nested objects, then each nested object's .GetType().IsSerializable would also have to be $true for this to work.

Petru Zaharia · Accepted Answer · 2017-07-20 20:08:18Z

10

Since Powershell 3.0, same approach as Jaco's answer but using PSSerializer.
It uses a CliXML format compatible with Export-Clixml & Import-Clixml and personally I find it easier to read.
In theory, supports a nested hierarchy up to [int32]::MaxValue levels-deep

#   Original data
$FruitsOriginal     =    Get-Fruits
#   Serialize and Deserialize data using PSSerializer:
$_TempCliXMLString  =   [System.Management.Automation.PSSerializer]::Serialize($FruitsOriginal, [int32]::MaxValue)
$FruitsNew          =   [System.Management.Automation.PSSerializer]::Deserialize($_TempCliXMLString)
#   Deep copy done.

answered Jul 20, 2017 at 20:08

Petru Zaharia

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2 Comments

DarkLite1 Over a year ago

That's a great tip! Thanks for adding 👍

Petru Zaharia Over a year ago

You're welcome. More than once I was fighting with $_.psobject.Copy() before stumbling on this solution :)

zmag · Accepted Answer · 2019-12-17 07:12:54Z

3

If you're copying an array of objects/value that contains all "truthy" values, or you want to quickly filter out null and "falsey" values, then this works great:

$FruitsNew = $FruitsOriginal|?{$_}

edited Dec 17, 2019 at 7:12

zmag

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answered Dec 17, 2019 at 6:50

Chase Colvin

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Comments

Cary · Accepted Answer · 2017-04-18 19:23:58Z

0

Depending on what you need to do with the objects, and if they're simple enough (as in your example), you could just replace them with a new object.

$NewFruits = $FruitsOriginal | %{ [PSCustomObject]@{ "Tasty Fruits" = $_.Type } }

answered Apr 18, 2017 at 19:23

Cary

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