Class: Util

Inherits:
Object
  • Object
show all
Defined in:
lib/clustertool/Util.rb

Overview

A few utility functions used by the clustering algorithms

Class Method Summary collapse

Class Method Details

.centroid(points) ⇒ Object

Caculates the centroid of a set of points

Example: >> Util.centroid([,[1,2,3],])

> [1,2,1]

Arguments: points: [[(Numeric), …], …]

Raises:

  • (ArgumentError) 


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# File 'lib/clustertool/Util.rb', line 32

def self.centroid(points)
  # Check boundary conditions and make sure each point has the same
  # dimension.
  return Array.new unless points.length > 0
  dim = points[0].length
  raise ArgumentError, "Can't calculate centroid of points with different
  dimensions" if points.any? { |p| p.length != dim }

  centroid = Array.new(points[0].length, 0)
  points.each do |point|
    point.each_with_index { |val, idx| centroid[idx] += val }
  end
  return centroid.map { |val| val.to_f / points.length }
end

.dist(point1, point2) ⇒ Object

Calculates the Euclidean Distance between two points of the same dimension.

Example: >> Util.dist(,[3,4])

> 5.0

Arguments: point1: [(Numeric), …] point2: [(Numeric), …]

Raises:

  • (ArgumentError) 


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# File 'lib/clustertool/Util.rb', line 13

def self.dist(point1, point2)
  # Start by making sure points have the same dimension
  raise ArgumentError, "Can't calculate distance of points with different
  dimensions" unless point1.length == point2.length

  pairs = point1.zip(point2)
  dist = 0
  pairs.each { |pair| dist += (pair[0] - pair[1])**2 }
  return Math.sqrt(dist)
end