Class: Rulp::Problem

Inherits:
Object show all
Defined in:
lib/rulp/rulp.rb

Instance Method Summary collapse

Constructor Details

#initialize(objective, objective_expression) ⇒ Problem

Returns a new instance of Problem.



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# File 'lib/rulp/rulp.rb', line 86

def initialize(objective, objective_expression)
  @objective = objective
  @variables = Set.new
  @objective_expression = objective_expression.kind_of?(LV) ? 1 * objective_expression : objective_expression
  @variables.merge(@objective_expression.variables)
  @constraints = []
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method_name, *args) ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 104

def method_missing(method_name, *args)
  self.call(method_name, *args)
end

Instance Method Details

#[](*constraints) ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 94

def [](*constraints)
  @constraints.concat(constraints)
  @variables.merge(constraints.map(&:variables).flatten)
  self
end

#bits ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 133

def bits
  bits = @variables.select{|x| x.kind_of?(BV) }.join(" ")
  return "\nBinary\n #{bits}" if(bits.length > 0)
end

#bounds ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 138

def bounds
  @variables.map{|var|
    next unless var.bounds
    " #{var.bounds}"
  }.compact.join("\n")
end

#call(using = nil, options = {}) ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 113

def call(using=nil, options={})
  Rulp.send(self.solver(using), self, options)
end

#constraints ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 117

def constraints
  constraints_str = @constraints.map.with_index{|constraint, i|
    " c#{i}: #{constraint}"
  }.join("\n").strip
  if constraints_str.empty?
    "0 #{@variables.first} = 0"
  else
    "  #{constraints_str}"
  end
end

#get_output_filename ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 145

def get_output_filename
  "/tmp/rulp-#{Random.rand(0..1000)}.lp"
end

#inspect ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 178

def inspect
  to_s
end

#integers ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 128

def integers
  ints = @variables.select{|x| x.kind_of?(IV) }.join(" ")
  return "\nGeneral\n #{ints}" if(ints.length > 0)
end

#output(filename = choose_file) ⇒ Object Also known as: save 



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# File 'lib/rulp/rulp.rb', line 149

def output(filename=choose_file)
  IO.write(filename, self)
end

#solve(opts = {}) ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 100

def solve(opts={})
  Rulp.send(self.solver, self, opts)
end

#solve_with(type, options = {}) ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 153

def solve_with(type, options={})
  filename = get_output_filename
  solver = SOLVERS[type].new(filename, options)

  "Writing problem".log(:info)
  IO.write(filename, self)

  `open #{filename}` if options[:open_definition]

  "Solving problem".log(:info)
  _, time = _profile{ solver.solve(options) }

  `open #{solver.outfile}` if options[:open_solution]

  "Solver took #{time}".log(:debug)

  "Parsing result".log(:info)
  solver.store_results(@variables)

  result = @objective_expression.evaluate

  "Objective: #{result}\n#{@variables.map{|v|[v.name, "=", v.value].join(' ') if v.value}.compact.join("\n")}".log(:debug)
  return result
end

#solver(solver = nil) ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 108

def solver(solver=nil)
  solver = solver || ENV["SOLVER"] || "Scip"
  solver = solver[0].upcase + solver[1..-1].downcase
end

#to_s ⇒ Object 



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# File 'lib/rulp/rulp.rb', line 182

def to_s
  %Q(
#{'  '*0}#{@objective}
#{'  '*0} obj: #{@objective_expression}
#{'  '*0}Subject to
#{'  '*0}#{constraints}
#{'  '*0}Bounds
#{'  '*0}#{bounds}#{integers}#{bits}
#{'  '*0}End
  )
end