CODEWITHSUNDEEP
pythonpowershell
WhyPok
WhyPok

Reputation: 13

Converting Python script to PowerShell

I'm trying to convert a Python script to PowerShell but I don't have any Python experience and it's getting long for a little piece of code.

def combinliste(seq, k):
    p = []
    i, imax = 0, 2**len(seq)-1
    while i<=imax:
        s = []
        j, jmax = 0, len(seq)-1
        while j<=jmax:
            if (i>>j)&1==1:
                s.append(seq[j])
            j += 1
        if len(s)==k:
            p.append(s)
        i += 1
    return p

I have made something but I really don't know if it's correct. What is += in PowerShell, is it same as Python?

function combinliste {
    Param($seq, $k)
    $p = @()
    $i; $imax = 0, [Math]::Pow(2, $seq.Count) - 1
    while ($i -le $jmax) {
        $s = @()
        $j, $jmax = 0, $seq.Count - 1
        while ($j -le $jmax) {
            if ($i -shr $j -band 1 -eq 1) {
                $s + ($seq ???? #I don't know how to do it here
            }
            $j #humm.. 1
        }
        if ($s.Count -eq $k) {
            $p + $s
        }
        $i #humm.. 1
        return $p
    }
}

I have tried few variations, but I'm lost.

Upvotes: 1

Views: 9306

Answers (2)

Mike Twc
Mike Twc

Reputation: 2355

function combinliste { param($seq,$k) 

$p = New-Object System.Collections.ArrayList

$i, $imax = 0, ([math]::Pow(2, $seq.Length) - 1)

while ($i -le $imax) {

     $s = New-Object System.Collections.ArrayList
     $j, $jmax = 0, ($seq.Length - 1)
     while ($j -le $jmax) {
         if((($i -shr $j) -band 1) -eq 1) {$s.Add($seq[$j]) | Out-Null}
         $j+=1
         }
     if ($s.Count -eq $k) {$p.Add($s) | Out-Null }
     $i+=1
   }

  return $p
}

$p = combinliste @('green', 'red', 'blue', 'white', 'yellow') 3

$p | foreach {$_ -join " | "}

Upvotes: 3

Ansgar Wiechers
Ansgar Wiechers

Reputation: 200373

The append() method updates an array in-place. The + operator in PowerShell doesn't do that. You need the += assignment operator for it.

$s += $seq[$j]

and

$p += $s

Alternatively you can use ArrayList collections instead of plain arrays:

$s = New-Object 'Collections.ArrayList'

and use their Add() method:

$s.Add($seq[$j]) | Out-Null

The trailing Out-Null is to suppress the index of the appended item that Add() outputs by default.

Side note: you probably need to put the return $p after the outer while loop, and $i; $imax = ... must be $i, $imax = ... for assigning two values to two variables in one statement.

Upvotes: 0

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