Get all combinations of an array - arrays

Question

I'm currently trying to make a function that gets all possible combinations of array values.
I have come up with a non function version but it's limited to 3 values so i'm trying to make a function out of it to become more Dynamic
I tried searching SO but could not find a powershell example of what i was trying to do, i could find a PHP version but i'm very limited in my PHP
PHP: How to get all possible combinations of 1D array?
Non-function Script
$name = 'First','Middle','Last'
$list = #()
foreach ($c1 in $name) {
foreach ($c2 in $name) {
foreach ($c3 in $name) {
if (($c1 -ne $c2) -and ($c2 -ne $c3) -and ($c3 -ne $c1))
{
$list += "$c1 $c2 $c3"
}
}
}
}
This gives me the result
First Middle Last
First Last Middle
Middle First Last
Middle Last First
Last First Middle
Last Middle First
I'm not sure how i would rearrange the values when i'm recursing the function, this is what i have so far:
<#
.Synopsis
Short description
.DESCRIPTION
Long description
.EXAMPLE
Example of how to use this cmdlet
.EXAMPLE
Another example of how to use this cmdlet
#>
function Get-Combinations
{
[CmdletBinding()]
[OutputType([int])]
Param
(
# Param1 help description
[Parameter(Mandatory=$true,
ValueFromPipelineByPropertyName=$true,
Position=0)]
[string[]]$Array,
# Param1 help description
[Parameter(Mandatory=$false,
ValueFromPipelineByPropertyName=$false,
Position=1)]
[string]$Temp,
# Param1 help description
[Parameter(Mandatory=$false,
ValueFromPipelineByPropertyName=$true,
Position=2)]
[string[]]$Return
)
Begin
{
Write-Verbose "Starting Function Get-Combinations with parameters `n`n$($Array | Out-String)`n$temp`n`n$($Return | Out-String)"
If ($Temp)
{
$Return = $Temp
}
$newArray = new-object system.collections.arraylist
}
Process
{
Write-Verbose ($return | Out-String)
For($i=0; $i -lt $Array.Length; $i++)
{
#Write-Verbose $i
$Array | ForEach-Object {$newArray.Add($_)}
$newArray.RemoveAt($i)
Write-Verbose ($newArray | Out-String)
if ($newArray.Count -le 1)
{
Get-Combinations -Array $newArray -Temp $Temp -Return $Return
}
else
{
$Return = $Temp
}
}
$newArray
}
End
{
Write-Verbose "Exiting Function Get-Combinations"
}
}
$combinations = #("First","First2","Middle","Last")
$Combos = Get-Combinations -Array $combinations
$Combos
But the output i'm getting is all over the place
First2
Last
First2
Last
First
First2
Middle
Last
First
First2
Middle
Last
28/08 Update
Getting closer but still getting weird output
<#
.Synopsis
Short description
.DESCRIPTION
Long description
.EXAMPLE
Example of how to use this cmdlet
.EXAMPLE
Another example of how to use this cmdlet
#>
function Get-Combinations
{
[CmdletBinding()]
[OutputType([int])]
Param
(
# Param1 help description
[Parameter(Mandatory=$true,
ValueFromPipelineByPropertyName=$true,
Position=0)]
[string[]]$Array,
# Param1 help description
[Parameter(Mandatory=$false,
ValueFromPipelineByPropertyName=$false,
Position=1)]
[string]$Temp,
# Param1 help description
[Parameter(Mandatory=$false,
ValueFromPipelineByPropertyName=$true,
Position=2)]
[string[]]$Return
)
Begin
{
Write-Verbose "Starting Function Get-Combinations with parameters `n`n$($Array | Out-String)`n$temp`n`n$($Return | Out-String)"
If ($Temp)
{
$Return += $Temp
}
#$newArray = new-object [System.Collections.ArrayList]
#$Array | ForEach-Object {$newArray.Add($_) | Out-Null}
[System.Collections.ArrayList]$newArray = $Array
}
Process
{
Write-Verbose "return -> $return"
For($i=0; $i -lt $Array.Length; $i++)
{
Write-Verbose "`$i -> $i"
$element = $newArray[0]
$newArray.RemoveAt(0)
Write-Verbose "`$newArray -> $newArray"
Write-Verbose "Element -> $element"
if ($newArray.Count -gt 0)
{
Get-Combinations -Array $newArray -Temp (($temp + " " +$element).Trim()) -Return $Return
}
else
{
$Return = $Temp + " " + $element
}
}
$return
}
End
{
Write-Verbose "Exiting Function Get-Combinations"
}
}
$combinations = #("First","First2","Middle","Last")
$return = #()
$Combos = Get-Combinations -Array $combinations -Return $return
$Combos
New output (Yes there is a space before the 'Last' value, no i have no idea why)
First First2 Middle Last
First First2 Last
First Middle Last
First Last
First2 Middle Last
First2 Last
Middle Last
Last

Answer 1

Here is my solution:
function Remove ($element, $list)
{
$newList = #()
$list | % { if ($_ -ne $element) { $newList += $_} }
return $newList
}
function Append ($head, $tail)
{
if ($tail.Count -eq 0)
{ return ,$head }
$result = #()
$tail | %{
$newList = ,$head
$_ | %{ $newList += $_ }
$result += ,$newList
}
return $result
}
function Permute ($list)
{
if ($list.Count -eq 0)
{ return #() }
$list | %{
$permutations = Permute (Remove $_ $list)
return Append $_ $permutations
}
}
cls
$list = "x", "y", "z", "t", "v"
$permutations = Permute $list
$permutations | %{
Write-Host ([string]::Join(", ", $_))
}
EDIT: the same in one function (Permute). This is cheating a bit, however since I replaced plain functions whith lambdas. You could replace recursive calls with a stack you handle yourself, but that would make the code unecessarily complex ...
function Permute ($list)
{
$global:remove = {
param ($element, $list)
$newList = #()
$list | % { if ($_ -ne $element) { $newList += $_} }
return $newList
}
$global:append = {
param ($head, $tail)
if ($tail.Count -eq 0)
{ return ,$head }
$result = #()
$tail | %{
$newList = ,$head
$_ | %{ $newList += $_ }
$result += ,$newList
}
return $result
}
if ($list.Count -eq 0)
{ return #() }
$list | %{
$permutations = Permute ($remove.Invoke($_, $list))
return $append.Invoke($_, $permutations)
}
}
cls
$list = "x", "y", "z", "t"
$permutations = Permute $list
$permutations | %{
Write-Host ([string]::Join(", ", $_))
}

Answer 2

I tried to learn something new and help you out but Im stuck. maybe this will help you get in the right direction but I dont know enough about Powershell recursion to figure this out. I converted the php to powershell and in theory it should work but it doesnt.
$array = #('Alpha', 'Beta', 'Gamma', 'Sigma')
function depth_picker([system.collections.arraylist]$arr,$temp_string, $collect)
{
if($temp_string -ne ""){$collect += $temp_string}
for($i = 0; $i -lt $arr.count;$i++)
{
[system.collections.arraylist]$arrCopy = $arr
$elem = $arrCopy[$i]
$arrCopy.removeRange($i,1)
if($arrCopy.count -gt 0){
depth_picker -arr $arrCopy -temp_string "$temp_string $elem" -collect $collect}
else{$collect += "$temp_string $elem"}
}
}
$collect = #()
depth_picker -arr $array -temp_string "" -collect $collect
$collect
It seems to work and will get you the first set of possibles:
Alpha
Alpha Beta
Alpha Beta Gamma
Alpha Beta Gamma Sigma
But for some reason that I cant figure out when it gets back to the previous functions and does $i++ then checks ($i -lt $arr.count) $arr.count it always 0 so it never goes to the next iteration to continue finding the possibilities.
Hopefully someone else can fix what I cant seem to figure out as I dont know enough about recursion. But it seems that with each level of depth called the previous depth level $arr variable and values is lost.

Answer 3

Here is my solution with a recursive function. It generates space separated strings but it's quite simple to split each element with $list[$i].split(" "):
function Get-Permutations
{
param ($array, $cur, $depth, $list)
$depth ++
for ($i = 0; $i -lt $array.Count; $i++)
{
$list += $cur+" "+$array[$i]
if ($depth -lt $array.Count)
{
$list = Get-Permutations $array ($cur+" "+$array[$i]) $depth $list
}
}
$list
}
$array = #("first","second","third","fourth")
$list = #()
$list = Get-Permutations $array "" 0 $list
$list

Answer 4

The solution posted by Micky Balladelli almost worked for me. Here is a version that does not duplicate values:
Function Get-Permutations
{
param ($array_in, $current, $depth, $array_out)
$depth++
$array_in = $array_in | select -Unique
for ($i = 0; $i -lt $array_in.Count; $i++)
{
$array_out += ($current+" "+$array_in[$i]).Trim()
if ($depth -lt $array_in.Count)
{
$array_out = Get-Permutations $array_in ($current+" "+$array_in[$i]) $depth $array_out
}
else {}
}
if(!($array_out -contains ($array_in -Join " "))) {}
for ($i = 0; $i -lt $array_out.Count; $i++)
{
$array_out[$i] = (($array_out[$i].Split(" ")) | select -Unique) -Join " "
}
$array_out | select -Unique
}