Module: Clusto

Extended by:
Clusto
Included in:
Clusto
Defined in:
lib/clusto.rb,
lib/clusto/point.rb,
lib/clusto/cluster.rb,
lib/clusto/distance.rb

Defined Under Namespace

Classes: Cluster, Distance, Point

Constant Summary collapse

INFINITY = 
+1.0/0
RADIANS_PER_DEGREES = 
Math::PI / 180
GREAT_CIRCLE_RADIUS = 
6371
DEFAULT_GRID_SIZE = 
8

Instance Method Summary collapse

Instance Method Details

#cluster(points, options = {}) ⇒ Object 



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# File 'lib/clusto.rb', line 21

def cluster(points, options={})
  bounds = options[:bounds] || Clusto.minimum_bounding_rectangle(points)
  distance_method = options[:distance_method] || :haversine
  grid_size = options[:grid_size] || DEFAULT_GRID_SIZE
  
  # Create clusters
  
  clusters = []
  
  x = bounds[0]
  y = bounds[3]
  w = bounds[2] - bounds[0]
  h = bounds[3] - bounds[1]
  grid_w = w / grid_size
  grid_h = h / grid_size
  
  column = 0
  row = 0
  
  (grid_size ** 2).times do |i|
    offset_x = x + (column * grid_w)
    offset_y = y - (row * grid_h)
    
    center = Clusto::Point.new(offset_x + (grid_w / 2), offset_y - (grid_h / 2))
    clusters.push(Clusto::Cluster.new(center))
    
    column = column+1
    if column == grid_size
      column = 0
      row = row+1
    end
  end
  
  # Assign points to clusters
  
  points.each do |point|
    distance = INFINITY
    nearest = nil

    clusters.each do |cluster|
      begin
        d = Clusto::Distance.send(distance_method, cluster.location, point)
      rescue NoMethodError
        raise "Unknown distance method '#{distance_method}."
      end
      
      if d < distance
        distance = d
        nearest = cluster
      end
    end

    nearest.points.push(point)
  end

  # Reposition clusters
  
  clusters.each { |c| c.reposition }
end

#minimum_bounding_rectangle(points) ⇒ Object 



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# File 'lib/clusto.rb', line 14

def minimum_bounding_rectangle(points)
  xs = points.collect { |p| p.x }.minmax
  ys = points.collect { |p| p.y }.minmax
  
  [xs[0], ys[0], xs[1], ys[1]]
end