content: """
  Testing Recursive feature elimination
  """
  import numpy as np
  from numpy.testing import assert_array_almost_equal, assert_array_equal
  from scipy import sparse
  
  from sklearn.feature_selection.rfe import RFE, RFECV
  from sklearn.datasets import load_iris, make_friedman1
  from sklearn.metrics import zero_one_loss
  from sklearn.svm import SVC, SVR
  from sklearn.ensemble import RandomForestClassifier
  from sklearn.model_selection import cross_val_score
  from sklearn.model_selection import GroupKFold
  
  from sklearn.utils import check_random_state
  from sklearn.utils.testing import ignore_warnings
  from sklearn.utils.testing import assert_greater, assert_equal, assert_true
  
  from sklearn.metrics import make_scorer
  from sklearn.metrics import get_scorer
  
  
  class MockClassifier(object):
      """
      Dummy classifier to test recursive feature elimination
      """
  
      def __init__(self, foo_param=0):
          self.foo_param = foo_param
  
      def fit(self, X, Y):
          assert_true(len(X) == len(Y))
          self.coef_ = np.ones(X.shape[1], dtype=np.float64)
          return self
  
      def predict(self, T):
          return T.shape[0]
  
      predict_proba = predict
      decision_function = predict
      transform = predict
  
      def score(self, X=None, Y=None):
          if self.foo_param > 1:
              score = 1.
          else:
              score = 0.
          return score
  
      def get_params(self, deep=True):
          return {'foo_param': self.foo_param}
  
      def set_params(self, **params):
          return self
  
  
  def test_rfe_features_importance():
      generator = check_random_state(0)
      iris = load_iris()
      X = np.c_[iris.data, generator.normal(size=(len(iris.data), 6))]
      y = iris.target
  
      clf = RandomForestClassifier(n_estimators=20,
                                   random_state=generator, max_depth=2)
      rfe = RFE(estimator=clf, n_features_to_select=4, step=0.1)
      rfe.fit(X, y)
      assert_equal(len(rfe.ranking_), X.shape[1])
  
      clf_svc = SVC(kernel="linear")
      rfe_svc = RFE(estimator=clf_svc, n_features_to_select=4, step=0.1)
      rfe_svc.fit(X, y)
  
      # Check if the supports are equal
      assert_array_equal(rfe.get_support(), rfe_svc.get_support())
  
  
  def test_rfe():
      generator = check_random_state(0)
      iris = load_iris()
      X = np.c_[iris.data, generator.normal(size=(len(iris.data), 6))]
      X_sparse = sparse.csr_matrix(X)
      y = iris.target
  
      # dense model
      clf = SVC(kernel="linear")
      rfe = RFE(estimator=clf, n_features_to_select=4, step=0.1)
      rfe.fit(X, y)
      X_r = rfe.transform(X)
      clf.fit(X_r, y)
      assert_equal(len(rfe.ranking_), X.shape[1])
  
      # sparse model
      clf_sparse = SVC(kernel="linear")
      rfe_sparse = RFE(estimator=clf_sparse, n_features_to_select=4, step=0.1)
      rfe_sparse.fit(X_sparse, y)
      X_r_sparse = rfe_sparse.transform(X_sparse)
  
      assert_equal(X_r.shape, iris.data.shape)
      assert_array_almost_equal(X_r[:10], iris.data[:10])
  
      assert_array_almost_equal(rfe.predict(X), clf.predict(iris.data))
      assert_equal(rfe.score(X, y), clf.score(iris.data, iris.target))
      assert_array_almost_equal(X_r, X_r_sparse.toarray())
  
  
  def test_rfe_mockclassifier():
      generator = check_random_state(0)
      iris = load_iris()
      X = np.c_[iris.data, generator.normal(size=(len(iris.data), 6))]
      y = iris.target
  
      # dense model
      clf = MockClassifier()
      rfe = RFE(estimator=clf, n_features_to_select=4, step=0.1)
      rfe.fit(X, y)
      X_r = rfe.transform(X)
      clf.fit(X_r, y)
      assert_equal(len(rfe.ranking_), X.shape[1])
      assert_equal(X_r.shape, iris.data.shape)
  
  
  def test_rfecv():
      generator = check_random_state(0)
      iris = load_iris()
      X = np.c_[iris.data, generator.normal(size=(len(iris.data), 6))]
      y = list(iris.target)   # regression test: list should be supported
  
      # Test using the score function
      rfecv = RFECV(estimator=SVC(kernel="linear"), step=1, cv=5)
      rfecv.fit(X, y)
      # non-regression test for missing worst feature:
      assert_equal(len(rfecv.grid_scores_), X.shape[1])
      assert_equal(len(rfecv.ranking_), X.shape[1])
      X_r = rfecv.transform(X)
  
      # All the noisy variable were filtered out
      assert_array_equal(X_r, iris.data)
  
      # same in sparse
      rfecv_sparse = RFECV(estimator=SVC(kernel="linear"), step=1, cv=5)
      X_sparse = sparse.csr_matrix(X)
      rfecv_sparse.fit(X_sparse, y)
      X_r_sparse = rfecv_sparse.transform(X_sparse)
      assert_array_equal(X_r_sparse.toarray(), iris.data)
  
      # Test using a customized loss function
      scoring = make_scorer(zero_one_loss, greater_is_better=False)
      rfecv = RFECV(estimator=SVC(kernel="linear"), step=1, cv=5,
                    scoring=scoring)
      ignore_warnings(rfecv.fit)(X, y)
      X_r = rfecv.transform(X)
      assert_array_equal(X_r, iris.data)
  
      # Test using a scorer
      scorer = get_scorer('accuracy')
      rfecv = RFECV(estimator=SVC(kernel="linear"), step=1, cv=5,
                    scoring=scorer)
      rfecv.fit(X, y)
      X_r = rfecv.transform(X)
      assert_array_equal(X_r, iris.data)
  
      # Test fix on grid_scores
      def test_scorer(estimator, X, y):
          return 1.0
      rfecv = RFECV(estimator=SVC(kernel="linear"), step=1, cv=5,
                    scoring=test_scorer)
      rfecv.fit(X, y)
      assert_array_equal(rfecv.grid_scores_, np.ones(len(rfecv.grid_scores_)))
  
      # Same as the first two tests, but with step=2
      rfecv = RFECV(estimator=SVC(kernel="linear"), step=2, cv=5)
      rfecv.fit(X, y)
      assert_equal(len(rfecv.grid_scores_), 6)
      assert_equal(len(rfecv.ranking_), X.shape[1])
      X_r = rfecv.transform(X)
      assert_array_equal(X_r, iris.data)
  
      rfecv_sparse = RFECV(estimator=SVC(kernel="linear"), step=2, cv=5)
      X_sparse = sparse.csr_matrix(X)
      rfecv_sparse.fit(X_sparse, y)
      X_r_sparse = rfecv_sparse.transform(X_sparse)
      assert_array_equal(X_r_sparse.toarray(), iris.data)
  
      # Verifying that steps < 1 don't blow up.
      rfecv_sparse = RFECV(estimator=SVC(kernel="linear"), step=.2, cv=5)
      X_sparse = sparse.csr_matrix(X)
      rfecv_sparse.fit(X_sparse, y)
      X_r_sparse = rfecv_sparse.transform(X_sparse)
      assert_array_equal(X_r_sparse.toarray(), iris.data)
  
  
  def test_rfecv_mockclassifier():
      generator = check_random_state(0)
      iris = load_iris()
      X = np.c_[iris.data, generator.normal(size=(len(iris.data), 6))]
      y = list(iris.target)   # regression test: list should be supported
  
      # Test using the score function
      rfecv = RFECV(estimator=MockClassifier(), step=1, cv=5)
      rfecv.fit(X, y)
      # non-regression test for missing worst feature:
      assert_equal(len(rfecv.grid_scores_), X.shape[1])
      assert_equal(len(rfecv.ranking_), X.shape[1])
  
  
  def test_rfecv_verbose_output():
      # Check verbose=1 is producing an output.
      from sklearn.externals.six.moves import cStringIO as StringIO
      import sys
      sys.stdout = StringIO()
  
      generator = check_random_state(0)
      iris = load_iris()
      X = np.c_[iris.data, generator.normal(size=(len(iris.data), 6))]
      y = list(iris.target)
  
      rfecv = RFECV(estimator=SVC(kernel="linear"), step=1, cv=5, verbose=1)
      rfecv.fit(X, y)
  
      verbose_output = sys.stdout
      verbose_output.seek(0)
      assert_greater(len(verbose_output.readline()), 0)
  
  
  def test_rfe_estimator_tags():
      rfe = RFE(SVC(kernel='linear'))
      assert_equal(rfe._estimator_type, "classifier")
      # make sure that cross-validation is stratified
      iris = load_iris()
      score = cross_val_score(rfe, iris.data, iris.target)
      assert_greater(score.min(), .7)
  
  
  def test_rfe_min_step():
      n_features = 10
      X, y = make_friedman1(n_samples=50, n_features=n_features, random_state=0)
      n_samples, n_features = X.shape
      estimator = SVR(kernel="linear")
  
      # Test when floor(step * n_features) <= 0
      selector = RFE(estimator, step=0.01)
      sel = selector.fit(X, y)
      assert_equal(sel.support_.sum(), n_features // 2)
  
      # Test when step is between (0,1) and floor(step * n_features) > 0
      selector = RFE(estimator, step=0.20)
      sel = selector.fit(X, y)
      assert_equal(sel.support_.sum(), n_features // 2)
  
      # Test when step is an integer
      selector = RFE(estimator, step=5)
      sel = selector.fit(X, y)
      assert_equal(sel.support_.sum(), n_features // 2)
  
  
  def test_number_of_subsets_of_features():
      # In RFE, 'number_of_subsets_of_features'
      # = the number of iterations in '_fit'
      # = max(ranking_)
      # = 1 + (n_features + step - n_features_to_select - 1) // step
      # After optimization #4534, this number
      # = 1 + np.ceil((n_features - n_features_to_select) / float(step))
      # This test case is to test their equivalence, refer to #4534 and #3824
  
      def formula1(n_features, n_features_to_select, step):
          return 1 + ((n_features + step - n_features_to_select - 1) // step)
  
      def formula2(n_features, n_features_to_select, step):
          return 1 + np.ceil((n_features - n_features_to_select) / float(step))
  
      # RFE
      # Case 1, n_features - n_features_to_select is divisible by step
      # Case 2, n_features - n_features_to_select is not divisible by step
      n_features_list = [11, 11]
      n_features_to_select_list = [3, 3]
      step_list = [2, 3]
      for n_features, n_features_to_select, step in zip(
              n_features_list, n_features_to_select_list, step_list):
          generator = check_random_state(43)
          X = generator.normal(size=(100, n_features))
          y = generator.rand(100).round()
          rfe = RFE(estimator=SVC(kernel="linear"),
                    n_features_to_select=n_features_to_select, step=step)
          rfe.fit(X, y)
          # this number also equals to the maximum of ranking_
          assert_equal(np.max(rfe.ranking_),
                       formula1(n_features, n_features_to_select, step))
          assert_equal(np.max(rfe.ranking_),
                       formula2(n_features, n_features_to_select, step))
  
      # In RFECV, 'fit' calls 'RFE._fit'
      # 'number_of_subsets_of_features' of RFE
      # = the size of 'grid_scores' of RFECV
      # = the number of iterations of the for loop before optimization #4534
  
      # RFECV, n_features_to_select = 1
      # Case 1, n_features - 1 is divisible by step
      # Case 2, n_features - 1 is not divisible by step
  
      n_features_to_select = 1
      n_features_list = [11, 10]
      step_list = [2, 2]
      for n_features, step in zip(n_features_list, step_list):
          generator = check_random_state(43)
          X = generator.normal(size=(100, n_features))
          y = generator.rand(100).round()
          rfecv = RFECV(estimator=SVC(kernel="linear"), step=step, cv=5)
          rfecv.fit(X, y)
  
          assert_equal(rfecv.grid_scores_.shape[0],
                       formula1(n_features, n_features_to_select, step))
          assert_equal(rfecv.grid_scores_.shape[0],
                       formula2(n_features, n_features_to_select, step))
  
  
  def test_rfe_cv_n_jobs():
      generator = check_random_state(0)
      iris = load_iris()
      X = np.c_[iris.data, generator.normal(size=(len(iris.data), 6))]
      y = iris.target
  
      rfecv = RFECV(estimator=SVC(kernel='linear'))
      rfecv.fit(X, y)
      rfecv_ranking = rfecv.ranking_
      rfecv_grid_scores = rfecv.grid_scores_
  
      rfecv.set_params(n_jobs=2)
      rfecv.fit(X, y)
      assert_array_almost_equal(rfecv.ranking_, rfecv_ranking)
      assert_array_almost_equal(rfecv.grid_scores_, rfecv_grid_scores)
  
  
  def test_rfe_cv_groups():
      generator = check_random_state(0)
      iris = load_iris()
      number_groups = 4
      groups = np.floor(np.linspace(0, number_groups, len(iris.target)))
      X = iris.data
      y = (iris.target > 0).astype(int)
  
      est_groups = RFECV(
          estimator=RandomForestClassifier(random_state=generator),
          step=1,
          scoring='accuracy',
          cv=GroupKFold(n_splits=2)
      )
      est_groups.fit(X, y, groups=groups)
      assert est_groups.n_features_ > 0
  