optimization-tuning1.py

import Orange

learner = Orange.classification.tree.TreeLearner()
voting = Orange.data.Table("voting")
tuner = Orange.tuning.Tune1Parameter(learner=learner,
                           parameter="min_subset",
                           values=[1, 2, 3, 4, 5, 10, 15, 20],
                           evaluate=Orange.evaluation.scoring.AUC, verbose=2)
classifier = tuner(voting)

print "Optimal setting: ", learner.min_subset

untuned = Orange.classification.tree.TreeLearner()
res = Orange.evaluation.testing.cross_validation([untuned, tuner], voting)
AUCs = Orange.evaluation.scoring.AUC(res)

print "Untuned tree: %5.3f" % AUCs[0]
print "Tuned tree: %5.3f" % AUCs[1]

learner = Orange.classification.tree.TreeLearner(min_subset=10).instance()
voting = Orange.data.Table("voting")
tuner = Orange.tuning.Tune1Parameter(learner=learner,
                    parameter=["split.continuous_split_constructor.min_subset",
                               "split.discrete_split_constructor.min_subset"],
                    values=[1, 2, 3, 4, 5, 10, 15, 20],
                    evaluate=Orange.evaluation.scoring.AUC, verbose=2)

classifier = tuner(voting)

print "Optimal setting: ", learner.split.continuous_split_constructor.min_subset