Functions/Get-NGram.ps1
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function Get-NGram { <# .SYNOPSIS Get the n-gram of a string. .DESCRIPTION An n-gram is a contiguous sequence of n items from a given sequence of text or speech. .EXAMPLE Get-NGram 'Pennsylvania' .EXAMPLE Get-NGram -String 'to be or not to be' -Size 3 -Separator ' ' .EXAMPLE Get-NGram 'Cys-Gly-Leu-Ser-Trp' 4 -Separator '-' .LINK http://en.wikipedia.org/wiki/N-gram https://communary.wordpress.com/ https://github.com/gravejester/Communary.PASM .INPUTS System.String .OUTPUTS System.Array .NOTES Author: Øyvind Kallstad Date: 07.11.2014 Version: 1.0 #> [CmdletBinding()] param ( [Parameter(Position = 0, Mandatory = $true)] [string] $String, # Defines the size of the n-gram. A size of 1 results in a unigram, a size of 2 (the default) results in a bigram, a size of 3 results in a trigram etc. [Parameter(Position = 1)] [int] $Size = 2, # Sequence separator [Parameter()] [string] $Separator ) try { if ($Size -lt 1) { Write-Warning 'Size cannot be less than 1'; return } if (-not([string]::IsNullOrEmpty($Separator))) { $s = $String.Split($Separator) # return if size is greater than the number of items in array after split if ($Size -gt $s.Count) { Write-Warning "Size cannot be longer than $($s.count)"; return } for ($i = 0; $i -le ($s.Count - $Size); $i++) { Write-Output (,($s[$i..($i + ($Size - 1))] -join $Separator)) } } else { # return if size is greater than string length if ($Size -gt $String.Length) { Write-Warning "Size cannot be longer than string length ($($String.Length))"; return } for ($i = 0; $i -lt ($String.Length - ($Size - 1)); $i++) { Write-Output (,($String.Substring($i,$Size))) } } } catch { Write-Warning $_.Exception.Message } } |