Functions/Get-HammingDistance.ps1
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function Get-HammingDistance { <# .SYNOPSIS Get the Hamming Distance between two strings or two positive integers. .DESCRIPTION The Hamming distance between two strings of equal length is the number of positions at which the corresponding symbols are different. In another way, it measures the minimum number of substitutions required to change one string into the other, or the minimum number of errors that could have transformed one string into the other. Note! Even though the original Hamming algorithm only works for strings of equal length, this function supports strings of unequal length as well. The function also calculates the Hamming distance between two positive integers (considered as binary values); that is, it calculates the number of bit substitutions required to change one integer into the other. .EXAMPLE Get-HammingDistance 'karolin' 'kathrin' Calculate the Hamming distance between the two strings. The result is 3. .EXAMPLE Get-HammingDistance 'karolin' 'kathrin' -NormalizedOutput Calculate the normalized Hamming distance between the two strings. The result is 0.571428571428571. .EXAMPLE Get-HammingDistance -Int1 61 -Int2 15 Calculate the hamming distance between 61 and 15. The result is 3. .LINK http://en.wikipedia.org/wiki/Hamming_distance https://communary.wordpress.com/ https://github.com/gravejester/Communary.PASM .NOTES Author: Øyvind Kallstad Date: 03.11.2014 Version: 1.0 #> [CmdletBinding(DefaultParameterSetName = 'String')] param ( [Parameter(Position = 0, Mandatory = $true, ParameterSetName = 'String')] [ValidateNotNullOrEmpty()] [string] $String1, [Parameter(Position = 1, Mandatory = $true, ParameterSetName = 'String')] [ValidateNotNullOrEmpty()] [string] $String2, [Parameter(Position = 0, Mandatory = $true, ParameterSetName = 'Integer')] [ValidateNotNullOrEmpty()] [uint32] $Int1, [Parameter(Position = 1, Mandatory = $true, ParameterSetName = 'Integer')] [ValidateNotNullOrEmpty()] [uint32] $Int2, # Makes matches case-sensitive. By default, matches are not case-sensitive. [Parameter(ParameterSetName = 'String')] [switch] $CaseSensitive, # Normalize the output value. When the output is not normalized the maximum value is the length of the longest string, and the minimum value is 0, # meaning that a value of 0 is a 100% match. When the output is normalized you get a value between 0 and 1, where 1 indicates a 100% match. [Parameter(ParameterSetName = 'String')] [switch] $NormalizeOutput ) try { if ($PSCmdlet.ParameterSetName -eq 'String') { # handle case insensitivity if (-not($CaseSensitive)) { $String1 = $String1.ToLowerInvariant() $String2 = $String2.ToLowerInvariant() } # set initial distance $distance = 0 # get max and min length of the input strings $maxLength = [Math]::Max($String1.Length,$String2.Length) $minLength = [Math]::Min($String1.Length,$String2.Length) # calculate distance for the length of the shortest string for ($i = 0; $i -lt $minLength; $i++) { if (-not($String1[$i] -ceq $String2[$i])) { $distance++ } } # add the remaining length to the distance $distance = $distance + ($maxLength - $minLength) if ($NormalizeOutput) { Write-Output (1 - ($distance / $maxLength)) } else { Write-Output $distance } } else { $distance = 0 $value = $Int1 -bxor $Int2 while ($value -ne 0) { $distance++ $value = $value -band ($value - 1) } Write-Output $distance } } catch { Write-Warning $_.Exception.Message } } |