Class: ConstraintSolver::Solution

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

Overview

This class represents a solution to a constraint satisfaction problem.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(variables, meritMap = {}, violation = 0) ⇒ Solution

Initialises a new solution with a list of variables. The variables must all have values assigned to them. Optionally, a map to map domain values of variables to their merit and a number designating the cost of violating constraints in the solution can be specified.



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# File 'lib/Solution.rb', line 12

def initialize(variables, meritMap={}, violation=0)
    if not variables.kind_of?(Array)
	variables = Array.new([ variables ])
    end
    if variables.inject(true) { |res,var| res & var.assigned? }
	@variables = Array.new
	variables.each { |variable|
	    @variables << variable.dup
	}
    else
	raise ArgumentError, "All variables must have values assigned to them!"
    end
    @merit = 0
    @variables.each { |var|
	@merit += meritMap[var.value] ? var.merit * meritMap[var.value] : var.merit
    }
    @violation = violation
    @merit -= @violation
end

Instance Attribute Details

#merit ⇒ Object (readonly)

Returns the value of attribute merit.



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# File 'lib/Solution.rb', line 6

def merit
  @merit
end

#variables ⇒ Object (readonly)

Returns the value of attribute variables.



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# File 'lib/Solution.rb', line 6

def variables
  @variables
end

#violation ⇒ Object (readonly)

Returns the value of attribute violation.



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# File 'lib/Solution.rb', line 6

def violation
  @violation
end

Instance Method Details

#<=>(solution) ⇒ Object 



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# File 'lib/Solution.rb', line 38

def <=>(solution)
    @value <=> solution.value
end

#==(solution) ⇒ Object 



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# File 'lib/Solution.rb', line 42

def ==(solution)
    return false unless solution.kind_of?(Solution)
    @variables == solution.variables and @merit == solution.merit and @violation == solution.violation
end

#each ⇒ Object 



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# File 'lib/Solution.rb', line 32

def each
    @variables.each { |variable|
	yield variable
    }
end

#to_s ⇒ Object 



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# File 'lib/Solution.rb', line 47

def to_s
    s = (@variables.collect { |variable|
	variable.to_s
    }).join(", ")
    s += ", merit " + @merit.to_s unless @merit.nil?
    s += ", violation " + @violation.to_s unless @violation.nil?
    return s
end