Class: Cbc::Model

Inherits:
Object
  • Object
show all
Defined in:
lib/ruby-cbc/model.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name: "ILP Problem") ⇒ Model

Returns a new instance of Model.



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# File 'lib/ruby-cbc/model.rb', line 21

def initialize(name: "ILP Problem")
  @vars = []
  @constraints = []
  @objective = nil
  @name = name
end

Instance Attribute Details

#constraints ⇒ Object

Returns the value of attribute constraints.



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# File 'lib/ruby-cbc/model.rb', line 19

def constraints
  @constraints
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/ruby-cbc/model.rb', line 19

def name
  @name
end

#objective ⇒ Object

Returns the value of attribute objective.



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# File 'lib/ruby-cbc/model.rb', line 19

def objective
  @objective
end

#vars ⇒ Object

Returns the value of attribute vars.



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# File 'lib/ruby-cbc/model.rb', line 19

def vars
  @vars
end

Instance Method Details

#bin_var(name: nil) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 36

def bin_var(name: nil)
  var(Ilp::Var::BINARY_KIND, 0..1, name)
end

#bin_var_array(length, names: nil) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 40

def bin_var_array(length, names: nil)
  array_var(length, Ilp::Var::BINARY_KIND, 0..1, names)
end

#cont_var(range = nil, name: nil) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 44

def cont_var(range = nil, name: nil)
  var(Ilp::Var::CONTINUOUS_KIND, range, name)
end

#cont_var_array(length, range = nil, names: nil) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 48

def cont_var_array(length, range = nil, names: nil)
  array_var(length, Ilp::Var::CONTINUOUS_KIND, range, names)
end

#enforce(*constraints) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 52

def enforce(*constraints)
  constraints.each do |constraint|
    if constraint.instance_of? Ilp::Constraint
      self.constraints << constraint
    elsif constraint.instance_of? Array
      self.constraints.concat constraint
    elsif constraint.instance_of? Hash
      to_add = constraint.map do |name, cons|
        cons.tap { |c| c.function_name = name.to_s }
      end
      self.constraints.concat to_add
    else
      puts "Not a constraint: #{constraint}"
    end
  end
end

#int_var(range = nil, name: nil) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 28

def int_var(range = nil, name: nil)
  var(Ilp::Var::INTEGER_KIND, range, name)
end

#int_var_array(length, range = nil, names: nil) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 32

def int_var_array(length, range = nil, names: nil)
  array_var(length, Ilp::Var::INTEGER_KIND, range, names)
end

#maximize(expression) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 74

def maximize(expression)
  @objective = Ilp::Objective.new(expression, Ilp::Objective::MAXIMIZE) if expression
  self
end

#minimize(expression) ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 69

def minimize(expression)
  @objective = Ilp::Objective.new(expression, Ilp::Objective::MINIMIZE) if expression
  self
end

#to_problem ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 79

def to_problem
  Cbc::Problem.from_model(self)
end

#to_s ⇒ Object 



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# File 'lib/ruby-cbc/model.rb', line 83

def to_s
  str = if objective
          "#{objective}\n"
        else
          "Maximize\n  0 #{vars.first}\n"
        end

  str << "\nSubject To\n"
  constraints.each do |cons|
    str << "  #{cons}\n"
  end
  bounded_vars = vars.select { |v| v.kind != Ilp::Var::BINARY_KIND }
  unless bounded_vars.empty?
    str << "\nBounds\n"
    bounded_vars.each do |v|
      str << "  #{lb_to_s(v.lower_bound)} <= #{v} <= #{ub_to_s(v.upper_bound)}\n"
    end
  end

  int_vars = vars.select { |v| v.kind == Ilp::Var::INTEGER_KIND }
  unless int_vars.empty?
    str << "\nGenerals\n"
    int_vars.each { |v| str << "  #{v}\n" }
  end

  bin_vars = vars.select { |v| v.kind == Ilp::Var::BINARY_KIND }
  unless bin_vars.empty?
    str << "\nBinaries\n"
    bin_vars.each { |v| str << "  #{v}\n" }
  end
  str << "\nEnd\n"

  str
end