Class: RGL::Edge::DirectedEdge

Inherits:
Object
  • Object
show all
Defined in:
lib/rgl/base.rb

Overview

An RGL::Edge is simply a directed pair (source -> target). Most library functions try do omit to instantiate edges. They instead use two vertex parameters for representing edges (see Graph#each_edge). If a client wants to store edges explicitly DirectedEdge or UnDirectedEdge instances are returned (i.e. Graph#edges).

Direct Known Subclasses

UnDirectedEdge

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(a, b) ⇒ DirectedEdge

Create a new DirectedEdge with source a and target b.



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# File 'lib/rgl/base.rb', line 45

def initialize(a, b)
  @source, @target = a, b
end

Instance Attribute Details

#source ⇒ Object

Returns the value of attribute source.



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# File 'lib/rgl/base.rb', line 36

def source
  @source
end

#target ⇒ Object

Returns the value of attribute target.



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# File 'lib/rgl/base.rb', line 36

def target
  @target
end

Class Method Details

.[](*a) ⇒ Object

Can be used to create an edge from a two element array.



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# File 'lib/rgl/base.rb', line 39

def self.[](*a)
  new(a[0], a[1])
end

Instance Method Details

#<=>(e) ⇒ Object

Sort support is dispatched to the <=> method of Array



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# File 'lib/rgl/base.rb', line 93

def <=> e
  self.to_a <=> e.to_a
end

#[](index) ⇒ Object

Edges can be indexed. edge.at(0) == edge.source, edge.at(n) == edge.target for all n>0. Edges can thus be used as a two element array.



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# File 'lib/rgl/base.rb', line 70

def [](index)
  index.zero? ? source : target
end

#eql?(edge) ⇒ Boolean Also known as: ==

Two directed edges (u,v) and (x,y) are equal iff u == x and v == y. eql? is needed when edges are inserted into a Set. eql? is aliased to ==.

Returns:

  • (Boolean) 


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# File 'lib/rgl/base.rb', line 51

def eql?(edge)
  (source == edge.source) && (target == edge.target)
end

#hash ⇒ Object 



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# File 'lib/rgl/base.rb', line 57

def hash
  source.hash ^ target.hash
end

#reverse ⇒ Edge

Returns (v,u) if self == (u,v).

Returns:



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# File 'lib/rgl/base.rb', line 63

def reverse
  self.class.new(target, source)
end

#to_a ⇒ Array

Returns the array [source,target].

Returns:

  • (Array) 


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# File 'lib/rgl/base.rb', line 87

def to_a
  [source, target]
end

#to_s ⇒ String Also known as: inspect

Returns string representation of the edge

Examples:

DirectedEdge[1,2].to_s == "(1-2)"

Returns:

  • (String) 


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# File 'lib/rgl/base.rb', line 78

def to_s
  "(#{source}-#{target})"
end