ObjectiveInstance¶

class ObjectiveInstance¶

The ObjectiveInstance object stores the information regarding a specific instance of an objective. The instances can be accessed through the function Objective.get of the parent entity.

value()¶

classmethod ObjectiveInstance.value()¶

Syntax¶

v = value()

Description¶

v = value() Get the current value of the objective instance

Output Arguments¶

v: The current value of the objective instance

Example¶

Create an indexed objective z, get an instance and display its value. Then solve the problem and display the value again.

ampl.eval('var x{i in 1..2} <= i;');
ampl.eval('maximize z{i in 1..2}: x[i];');
z = ampl.getObjective('z');
instance = z.get(1);
instance.value
ampl.solve;
instance.value

gives:

ans =
  0

ans =
  1

astatus¶

classmethod ObjectiveInstance.astatus()¶

Syntax¶

v = astatus

Description¶

astatus Return the AMPL status for this objective instance.

Output Arguments¶

v: The AMPL status for this objective instance.

Example¶

Create an indexed objective z, get an instance and display its status. Then solve the problem and display it again.

ampl.eval('var x{i in 1..2} <= i;');
ampl.eval('maximize z{i in 1..2}: x[i];');
z = ampl.getObjective('z');
instance = z.get(1);
instance.astatus
ampl.solve;
instance.astatus

gives:

ans =
in

ans =
in

exitcode¶

classmethod ObjectiveInstance.exitcode()¶

Syntax¶

v = exitcode

Description¶

exitcode Get exit code returned by solver after most recent solve with this objective.

Output Arguments¶

v: The exit code returned by solver after most recent solve with this objective.

Example¶

Create an indexed objective z, get an instance and display its exitcode. Then solve the problem and display it again.

ampl.eval('var x{i in 1..2} <= i;');
ampl.eval('maximize z{i in 1..2}: x[i];');
z = ampl.getObjective('z');
instance = z.get(1);
instance.exitcode
ampl.solve;
instance.exitcode

gives:

ans =
0

ans =
0

message¶

classmethod ObjectiveInstance.message()¶

Syntax¶

v = message

Description¶

message Get the result message returned by solver after most recent solve with this objective.

Output Arguments¶

v: The result message returned by solver after most recent solve with this objective

Example¶

Create an indexed objective z, get an instance and display the solver message. Then solve the problem and display it again.

ampl.eval('var x{i in 1..2} <= i;');
ampl.eval('maximize z{i in 1..2}: x[i];');
z = ampl.getObjective('z');
instance = z.get(1);
instance.message
ampl.solve;
instance.message

gives:

ans =
?

ans =
CBC 2.8.2 optimal, objective -1
0 iterations

result¶

classmethod ObjectiveInstance.result()¶

Syntax¶

v = result

Description¶

result Get the result string returned by solver after most recent solve with this objective.

Output Arguments¶

v: The result string returned by solver after most recent solve with this objective.

Example¶

Create an indexed objective z, get an instance and display its result string. Then solve the problem and display it again.

ampl.eval('var x{i in 1..2} <= i;');
ampl.eval('maximize z{i in 1..2}: x[i];');
z = ampl.getObjective('z');
instance = z.get(1);
instance.result
ampl.solve;
instance.result

gives:

ans =
?

ans =
solved

Objective

Parameter