Powershell break a long array into a array of array with length of N in one line?

Question

For example, given a list 1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8 and a number 4, it returns a list of list with length of 4, that is (1, 2, 3, 4), (5, 6, 7, 8),

Answer 1

@Shay Levy Answer: if you change the value of a to 1..15 then your solution not working anymore ( Peter Reavy comment )

So this worked for me:

$a = 1..15
$z=for($i=0; $i -lt $a.length; $i+=4){if ($a.length -gt ($i+3)) { ,($a[$i]..$a[$i+3])} else { ,($a[$i]..$a[-1])}}
$z.count

Answer 2

Clear-Host

$s = 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18

$count = $s.Length

$split = $count/2

$split --

$b = $s[0..$split]

$split ++

$a = $s[$split..$count]

write-host "first array"

$b

write-host "next array"

$a

#clean up
Get-Variable -Exclude PWD,*Preference | Remove-Variable -EA 0

Answer 3

This is a bit old, but I figured I'd throw in the method I use for splitting an array into chunks. You can use Group-Object with a constructed property:

$bigList = 1..1000

$counter = [pscustomobject] @{ Value = 0 }
$groupSize = 100

$groups = $bigList | Group-Object -Property { [math]::Floor($counter.Value++ / $groupSize) }

$groups will be a collection of GroupInfo objects; in this case, each group will have exactly 100 elements (accessible as $groups[0].Group, $groups[1].Group, and so on.) I use an object property for the counter to avoid scoping issues inside the -Property script block, since a simple $i++ doesn't write back to the original variable. Alternatively, you can use $script:counter = 0 and $script:counter++ and get the same effect without a custom object.

Answer 4

$a = 1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,0
$b = 0..([Math]::ceiling($a.Length / 4) - 1) | 
    % {  @(, $a[($_*4)..($_*4 + 4 - 1)]) } 

Don't know why I had to put a comma after (.

Answer 5

PS> $a = 1..16
PS> $z=for($i=0; $i -lt $a.length; $i+=4){ ,($a[$i]..$a[$i+3])}
PS> $z.count
4    

PS> $z[0]
1
2
3
4

PS> $z[1]
5
6
7
8

PS> $z[2]
9
10
11
12

PS> $z[3]
13
14
15
16

Answer 6

Wrote this in 2009 PowerShell Split-Every Function

Probably can be improved.

Function Split-Every($list, $count=4) {
    $aggregateList = @()

    $blocks = [Math]::Floor($list.Count / $count)
    $leftOver = $list.Count % $count
    for($i=0; $i -lt $blocks; $i++) {
        $end = $count * ($i + 1) - 1

        $aggregateList += @(,$list[$start..$end])
        $start = $end + 1
    }    
    if($leftOver -gt 0) {
        $aggregateList += @(,$list[$start..($end+$leftOver)])
    }

    $aggregateList    
}

$s = 1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8

$r = Split-Every $s 4

$r[0]
""
$r[1]
""
$r[2]
""
$r[3]