Class SolnPoolInterface

Creates a new SolnPoolInterface.

The solution pool interface is exposed by the top-level Cplex class as Cplex.solution.pool. This constructor is not meant to be used externally.

Overrides: object.__init__

Returns the objective value for a member of the solution pool.

Example usage:

>>> import cplex
>>> c = cplex.Cplex()
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.solve()
>>> obj_val = c.solution.pool.get_objective_value(0)
>>> abs(obj_val - 499.0) < 1e-6
True

Returns the values of a set of variables for a given solution.

Can be called by four forms.

>>> import cplex
>>> c = cplex.Cplex()
>>> c.parameters.randomseed.set(1)
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.solve()
>>> c.solution.pool.get_values(1, 2)
244.0
>>> abs(c.solution.pool.get_values(1, "x2"))
0.0
>>> val = c.solution.pool.get_values(1, ["x2", 2])
>>> [x if x else 0.0 for x in val]
[0.0, 244.0]
>>> val = c.solution.pool.get_values(1)
>>> val[2]
244.0

Returns a set of linear slacks for a given solution.

Can be called by four forms.

>>> import cplex
>>> c = cplex.Cplex()
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.solve()
>>> c.solution.pool.get_linear_slacks(2, 1)
0.0
>>> c.solution.pool.get_linear_slacks(2, "c2")
0.0
>>> c.solution.pool.get_linear_slacks(2, ["c2", 1])
[0.0, 0.0]
>>> linslack = c.solution.pool.get_linear_slacks(2)
>>> abs(linslack[2]) < 1e-6
True

Returns a set of quadratic slacks for a given solution.

Can be called by four forms.

>>> import cplex
>>> c = cplex.Cplex()
>>> c.parameters.randomseed.set(1)
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("miqcp.lp")
>>> c.solve()
>>> var = c.solution.pool.get_quadratic_slacks(1, 1)
>>> var = c.solution.pool.get_quadratic_slacks(1, "QC3")
>>> vars = c.solution.pool.get_quadratic_slacks(1, ["QC3", 1])
>>> vars = c.solution.pool.get_quadratic_slacks(1)

Returns the integer quality of a given solution.

The integer quality of a solution can either be a single attribute of solution.pool.quality_metrics or a sequence of such attributes.

Note

This corresponds to the CPLEX callable library function CPXgetsolnpoolintquality.

>>> import cplex
>>> c = cplex.Cplex()
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.solve()
>>> quality_metric = c.solution.pool.quality_metric
>>> misi = quality_metric.max_indicator_slack_infeasibility
>>> c.solution.pool.get_integer_quality(1, misi)
-1

Returns the float quality of a given solution.

The float quality of a solution can either be a single attribute of solution.pool.quality_metrics or a sequence of such attributes.

Note

This corresponds to the CPLEX callable library function CPXgetsolnpooldblquality.

>>> import cplex
>>> c = cplex.Cplex()
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.solve()
>>> qual = c.solution.pool.get_float_quality(1,
                         c.solution.pool.quality_metric.max_indicator_slack_infeasibility)
>>> abs(qual) < 1.e-6
True

Returns the average among the objective values in the solution pool.

Example usage:

>>> import cplex
>>> c = cplex.Cplex()
>>> c.parameters.randomseed.set(1)
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.solve()
>>> mov = c.solution.pool.get_mean_objective_value()

Deletes solutions from the solution pool.

There are four forms by which pool.delete may be called.

pool.delete()

deletes all solutions from the problem.

pool.delete(i)

i must be a solution name or index. Deletes the solution whose index or name is i.

pool.delete(s)

s must be a sequence of solution names or indices. Deletes the solutions with names or indices contained within s. Equivalent to [pool.delete(i) for i in s].

pool.delete(begin, end)

begin and end must be solution indices or solution names. Deletes the solutions with indices between begin and end, inclusive of end. Equivalent to pool.delete(range(begin, end + 1)). This will give the best performance when deleting batches of solutions from the solution pool.

See CPXdelsolnpoolsolns in the Callable Library Reference Manual for more detail.

Example usage:

>>> import cplex
>>> c = cplex.Cplex()
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.parameters.randomseed.set(1)
>>> c.parameters.mip.limits.populate.set(5)
>>> c.populate_solution_pool()
>>> names = c.solution.pool.get_names()
>>> c.solution.pool.delete(1)
>>> n = c.solution.pool.get_names()
>>> del names[1]
>>> n == names
True
>>> c.solution.pool.delete(names[1])
>>> n = c.solution.pool.get_names()
>>> names.remove(names[1])
>>> n == names
True
>>> c.solution.pool.delete([names[1], 0])
>>> n = c.solution.pool.get_names()
>>> names.remove(names[1])
>>> del names[0]
>>> n == names
True
>>> c.solution.pool.delete()
>>> c.solution.pool.get_names()
[]

Returns the names of a set of solutions.

There are four forms by which solution.pool.get_names may be called.

solution.pool.get_names()

return the names of all solutions from the problem.

solution.pool.get_names(i)

i must be a solution index. Returns the name of row i.

solution.pool.get_names(s)

s must be a sequence of row indices. Returns the names of the solutions with indices the members of s. Equivalent to [solution.pool.get_names(i) for i in s]

solution.pool.get_names(begin, end)

begin and end must be solution indices. Returns the names of the solutions with indices between begin and end, inclusive of end. Equivalent to solution.pool.get_names(range(begin, end + 1)).

>>> import cplex
>>> c = cplex.Cplex()
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.parameters.randomseed.set(1)
>>> c.parameters.mip.limits.populate.set(10)
>>> c.populate_solution_pool()
>>> names = c.solution.pool.get_names()
>>> names[1] == c.solution.pool.get_names(1)
True
>>> [names[i] for i in [1,2]] == c.solution.pool.get_names([1,2])
True
>>> names[1:5] == c.solution.pool.get_names(1, 4)
True

Returns the number of solution pool members that have been replaced.

Example usage:

>>> import cplex
>>> c = cplex.Cplex()
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.solve()
>>> c.solution.pool.get_num_replaced()
0

Returns the number of solutions in the solution pool.

Example usage:

>>> import cplex
>>> c = cplex.Cplex()
>>> c.parameters.randomseed.set(1)
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.solve()
>>> num = c.solution.pool.get_num()

Writes solutions to a file.

If no second argument is provided, all solutions are written to file.

If a second argument is provided, it is the index of a solution in the solution pool. Only that solution will be written to file.

>>> import cplex
>>> c = cplex.Cplex()
>>> out = c.set_results_stream(None)
>>> out = c.set_log_stream(None)
>>> c.read("ind.lp")
>>> c.parameters.randomseed.set(1)
>>> c.parameters.mip.limits.populate.set(10)
>>> c.populate_solution_pool()
>>> c.solution.pool.write("ind.sol",4)

Returns an object containing measures of the quality of the specified solution.

See QualityMetrics