PowerShell Cmdlet for Splitting an Array - Svendsen TechI wrote a couple of advanced functions (it's just a few lines of code) for splitting an array/collection into chunks/parts for later processing in the pipeline (or otherwise) as smaller arrays. It's pretty simple, but quite useful for a number of scenarios. I've found myself needing this from time to time, so I finally decided to write a generic version of it.

Its performance on very large collections won't be too good, but I haven't actually benchmarked it or tested it extensively (yet). Array concatenation is something PowerShell does not do efficiently (I seem to remember the reasons for this being good though (creating a copy of the array)), and array concatenation seems difficult to avoid, and is used in this cmdlet, so there will be a performance penalty due to that.

I'm putting up two versions. The version called Split-Collection.ps1.txt works only with pipeline input The other one, called Split-CollectionParam.ps1.txt, also works correctly on a collection passed in as the parameter -Collection. In the latter version I use foreach () on the collection, which enumerates the entire collection and thus potentially could be more memory-intensive than the version working strictly with pipeline input, one element at the time, but you might see a performance gain as foreach loops are generally a lot faster than ForEach-Object. The latter one (with param) is more versatile as it works with both pipeline input and input passed as a parameter and would generally be recommended unless you know you need the other one.

Examples

It works like this:
PS C:\> 1..10 | Split-Collection -Count 2 | %{ $_ -join ', ' }
1, 2
3, 4
5, 6
7, 8
9, 10

PS C:\> (1..10 | Split-Collection -Count 2 | %{ $_ -join ', ' }).Count
5

PS C:\> 1..10 | Split-Collection -Count 5 | %{ $_ -join ', ' }
1, 2, 3, 4, 5
6, 7, 8, 9, 10

PS C:\> (1..10 | Split-Collection -Count 5 | %{ $_ -join ', ' }).Count
2

And you also get the remainder (requires its own logic...) if it doesn't divide evenly:

PS C:\> 1..10 | Split-Collection -Count 3 | %{ $_ -join ', ' }
1, 2, 3
4, 5, 6
7, 8, 9
10

PS C:\> (1..10 | Split-Collection -Count 3 | %{ $_ -join ', ' }).Count
4

Here's an example where I dot-source Split-CollectionParam.ps1 ("the second version") and pass in a collection as a parameter.

PS D:\> . D:\Dropbox\PowerShell\Split-CollectionParam.ps1

PS D:\> Split-Collection -Collection (1..10) -Count 5 | %{ $_ -join ', ' }
1, 2, 3, 4, 5
6, 7, 8, 9, 10

PS D:\> (Split-Collection -Collection (1..10) -Count 5 | %{ $_ -join ', ' }).Count
2


Code

Split-CollectionParam.ps1.txt

function Split-Collection {
    [CmdletBinding()]
    param(
        [Parameter(ValueFromPipeline=$true,ValueFromPipelineByPropertyName=$true)] $Collection,
        [Parameter(Mandatory=$true)][ValidateRange(1, 247483647)][int] $Count)
    begin {
        $Ctr = 0
        $Array = @()
        $TempArray = @()
    }
    process {
        foreach ($e in $Collection) {
            if (++$Ctr -eq $Count) {
                $Ctr = 0
                $Array += , @($TempArray + $e)
                $TempArray = @()
                continue
            }
            $TempArray += $e
        }
    }
    end {
        if ($TempArray) { $Array += , $TempArray }
        $Array
    }
}

Split-Collection.ps1.txt

function Split-Collection {
    [CmdletBinding()]
    param(
        [Parameter(ValueFromPipeline=$true)] $Collection,
        [Parameter(Mandatory=$true)][ValidateRange(1, 247483647)][int] $Count)
    begin {
        $Ctr = 0
        $Arrays = @()
        $TempArray = @()
    }
    process {
        if (++$Ctr -eq $Count) {
            $Ctr = 0
            $Arrays += , @($TempArray + $_)
            $TempArray = @()
            return
        }
        $TempArray += $_
    }
    end {
        if ($TempArray) { $Arrays += , $TempArray }
        $Arrays
    }
}

Download

*Split-CollectionParam.ps1.txt - ('''recommended''') right-click and save/download. *Split-Collection.ps1.txt - right-click and save/download.

''2014-01-11: Put up two versions and documented briefly.

''2014-01-11: Renamed the parameter -ChunkSize to -Count.''     Powershell     Windows     All Categories

Google custom search of this website only

Minimum cookies is the standard setting. This website uses Google Analytics and Google Ads, and these products may set cookies. By continuing to use this website, you accept this.

If you want to reward my efforts