gibbels-algorithms

1.0.3

scripts/levenshtein/Test-LevenshteinDistance.ps1

 <#
 .SYNOPSIS
  Checks the Levenshtein Distance (also known as Edit Distance) between two strings.
  
 .PARAMETER Source
  The source string you want to test.
  
 .PARAMETER Target
  The target string you want to test against.
#>
function Test-LevenshteinDistance {

    param( 
        [Parameter(Position=0,Mandatory=$True)]
        [string]$Source,
        [Parameter(Position=1,Mandatory=$True)]
        [string]$Target
    )

    $sourceLength = $Source.Length
    $targetLength = $Target.Length

    $grid = New-Object -TypeName 'int[,]' -ArgumentList  ($sourceLength + 1),($targetLength + 1)

    for ($i = 0; $i -le $sourceLength; $i++) {
       $grid[$i, 0] = $i
    }

    for ($i = 0; $i -le $targetLength; $i++) {
       $grid[0, $i] = $i
    }

    for($i = 1; $i -le $sourceLength; $i++) {
      for($j  = 1; $j -le $targetLength; $j++) {
         $cost = 1
         if($Target[$j - 1] -eq $Source[$i - 1]) {
            $cost = 0
         } 
         $grid[$i, $j] = [System.Math]::Min(([System.Math]::Min((($grid[($i - 1), $j]) + 1), (($grid[$i, ($j - 1)]) + 1))), (($grid[($i - 1), ($j - 1)]) + $cost))
      }
    } 
    return $grid[$sourceLength,$targetLength]
}