Functions/GenXdev.AI/Get-VectorSimilarity.ps1
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Part of PowerShell module : GenXdev.AI Original cmdlet filename : Get-VectorSimilarity.ps1 Original author : René Vaessen / GenXdev Version : 1.300.2025 ################################################################################ Copyright (c) René Vaessen / GenXdev Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ################################################################################> ############################################################################### <# .SYNOPSIS Calculates the cosine similarity between two vectors, returning a value between 0 and 1. .DESCRIPTION This function takes two numerical vectors (arrays) as input and computes their cosine similarity. The result indicates how closely related the vectors are, with 0 meaning completely dissimilar and 1 meaning identical. .PARAMETER Vector1 The first vector as an array of numbers (e.g., [0.12, -0.45, 0.89]). Must be the same length as Vector2. .PARAMETER Vector2 The second vector as an array of numbers (e.g., [0.15, -0.40, 0.92]). Must be the same length as Vector1. .EXAMPLE $v1 = @(0.12, -0.45, 0.89) $v2 = @(0.15, -0.40, 0.92) Get-VectorSimilarity -Vector1 $v1 -Vector2 $v2 Returns approximately 0.998, indicating high similarity #> function Get-VectorSimilarity { [CmdletBinding()] [OutputType([double])] param ( ######################################################################## [Parameter( Mandatory = $true, Position = 0, HelpMessage = 'First vector array of numbers' )] [double[]]$Vector1, ######################################################################## [Parameter( Mandatory = $true, Position = 1, HelpMessage = 'Second vector array of numbers' )] [double[]]$Vector2 ######################################################################## ) begin { Microsoft.PowerShell.Utility\Write-Verbose 'Validating input vectors...' # check for null vectors if (-not $Vector1 -or -not $Vector2) { Microsoft.PowerShell.Utility\Write-Error 'Both Vector1 and Vector2 must contain values.' return $null } # verify vectors have matching lengths if ($Vector1.Length -ne $Vector2.Length) { Microsoft.PowerShell.Utility\Write-Error 'Vector1 and Vector2 must have the same length.' return $null } # ensure vectors are not empty if ($Vector1.Length -eq 0) { Microsoft.PowerShell.Utility\Write-Error 'Vectors cannot be empty.' return $null } } process { try { Microsoft.PowerShell.Utility\Write-Verbose 'Calculating vector similarity...' # compute the dot product of the two vectors $dotProduct = 0.0 for ($i = 0; $i -lt $Vector1.Length; $i++) { $dotProduct += $Vector1[$i] * $Vector2[$i] } # calculate the magnitude (euclidean norm) of each vector $magnitude1 = 0.0 $magnitude2 = 0.0 for ($i = 0; $i -lt $Vector1.Length; $i++) { $magnitude1 += [Math]::Pow($Vector1[$i], 2) $magnitude2 += [Math]::Pow($Vector2[$i], 2) } $magnitude1 = [Math]::Sqrt($magnitude1) $magnitude2 = [Math]::Sqrt($magnitude2) # prevent division by zero for zero-magnitude vectors if ($magnitude1 -eq 0 -or $magnitude2 -eq 0) { Microsoft.PowerShell.Utility\Write-Verbose ('One or both vectors have zero magnitude. ' + 'Similarity is undefined.') return 0.0 } # calculate final cosine similarity $similarity = $dotProduct / ($magnitude1 * $magnitude2) # normalize result to 0-1 range $normalizedSimilarity = [Math]::Min([Math]::Max($similarity, -1), 1) $normalizedSimilarity = ($normalizedSimilarity + 1) / 2 Microsoft.PowerShell.Utility\Write-Verbose 'Similarity calculation complete' return [math]::Round($normalizedSimilarity, 6) } catch { Microsoft.PowerShell.Utility\Write-Error "Error calculating similarity: $_" return $null } } end { } } |