Class: MOSAIK::Graph::Reducer

Inherits:
Object
  • Object
show all
Defined in:
lib/mosaik/graph/reducer.rb

Overview

Reduce the graph (aggregate common edges and normalize weights)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options, graph) ⇒ Reducer

Returns a new instance of Reducer.



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# File 'lib/mosaik/graph/reducer.rb', line 13

def initialize(options, graph)
  @options = options
  @graph = graph
end

Instance Attribute Details

#graph ⇒ Object (readonly)

Returns the value of attribute graph.



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# File 'lib/mosaik/graph/reducer.rb', line 11

def graph
  @graph
end

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/mosaik/graph/reducer.rb', line 11

def options
  @options
end

Instance Method Details

#call(directed: false) ⇒ Object 



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# File 'lib/mosaik/graph/reducer.rb', line 18

def call(directed: false)
  # Iterate over all combinations of vertices
  weights = graph.vertices.keys.combination(2).filter_map do |v1, v2|
    # Find all edges between the two vertices
    edges = Set.new(graph.find_edges(v1, v2) + graph.find_edges(v2, v1))

    # Calculate the weight for the aggregate edge
    weight = 0.0

    # Add weight for structural coupling
    weight += options[:structural] * edges
      .select { |e| e.attributes[:type] == "structural" }
      .sum { |e| e.attributes.fetch(:weight, 0.0) }

    # Add weight for logical coupling
    weight += options[:logical] * edges
      .select { |e| e.attributes[:type] == "logical" }
      .sum { |e| e.attributes.fetch(:weight, 0.0) }

    # Add weight for contributor coupling
    weight += options[:contributor] * edges
      .select { |e| e.attributes[:type] == "contributor" }
      .sum { |e| e.attributes.fetch(:weight, 0.0) }

    # Don't add zero weights
    next if weight.zero?

    # Return vertices and weights
    [v1, v2, weight]
  end

  # Remove all existing edges
  graph.vertices.each_value { |v| v.edges.clear }

  # Set graph directionality
  graph.directed = directed

  # Add new edges
  weights.each { |v1, v2, weight| graph.add_edge(v1, v2, weight:) unless weight.zero? }
end