def test_one_hot_encoder_not_fitted():
X = np.array([['a'], ['b']])
enc = OneHotEncoder(categories=['a', 'b'])
msg = ("This OneHotEncoder instance is not fitted yet. "
"Call 'fit' with appropriate arguments before using this method.")
with pytest.raises(NotFittedError, match=msg):
enc.transform(X)
def test_one_hot_encoder_feature_names_drop(drop, expected_names):
X = [['c', 2, 'a'], ['b', 2, 'b']]
ohe = OneHotEncoder(drop=drop)
ohe.fit(X)
feature_names = ohe.get_feature_names()
assert isinstance(feature_names, np.ndarray)
assert_array_equal(expected_names, feature_names)
def test_one_hot_encoder(X):
Xtr = check_categorical_onehot(np.array(X)[:, [0]])
assert_allclose(Xtr, [[0, 1], [1, 0]])
Xtr = check_categorical_onehot(np.array(X)[:, [0, 1]])
assert_allclose(Xtr, [[0, 1, 1, 0], [1, 0, 0, 1]])
Xtr = OneHotEncoder(categories='auto').fit_transform(X)
assert_allclose(Xtr.toarray(), [[0, 1, 1, 0, 1], [1, 0, 0, 1, 1]])
def test_one_hot_encoder_categories(X, cat_exp, cat_dtype):
# order of categories should not depend on order of samples
for Xi in [X, X[::-1]]:
enc = OneHotEncoder(categories='auto')
enc.fit(Xi)
# assert enc.categories == 'auto'
assert isinstance(enc.categories_, list)
for res, exp in zip(enc.categories_, cat_exp):
assert res.tolist() == exp
assert np.issubdtype(res.dtype, cat_dtype)
def test_one_hot_encoder_specified_categories_mixed_columns():
# multiple columns
X = np.array([['a', 'b'], [0, 2]], dtype=object).T
enc = OneHotEncoder(categories=[['a', 'b', 'c'], [0, 1, 2]])
exp = np.array([[1., 0., 0., 1., 0., 0.], [0., 1., 0., 0., 0., 1.]])
assert_array_equal(enc.fit_transform(X).toarray(), exp)
assert enc.categories_[0].tolist() == ['a', 'b', 'c']
assert np.issubdtype(enc.categories_[0].dtype, np.object_)
assert enc.categories_[1].tolist() == [0, 1, 2]
# integer categories but from object dtype data
assert np.issubdtype(enc.categories_[1].dtype, np.object_)
def test_one_hot_encoder_drop_manual():
cats_to_drop = ['def', 12, 3, 56]
enc = OneHotEncoder(drop=cats_to_drop)
X = [['abc', 12, 2, 55], ['def', 12, 1, 55], ['def', 12, 3, 56]]
trans = enc.fit_transform(X).toarray()
exp = [[1, 0, 1, 1], [0, 1, 0, 1], [0, 0, 0, 0]]
assert_array_equal(trans, exp)
dropped_cats = [
cat[feature] for cat, feature in zip(enc.categories_, enc.drop_idx_)
]
assert_array_equal(dropped_cats, cats_to_drop)
assert_array_equal(np.array(X, dtype=object), enc.inverse_transform(trans))
def test_one_hot_encoder_set_params():
X = np.array([[1, 2]]).T
oh = OneHotEncoder()
# set params on not yet fitted object
oh.set_params(categories=[[0, 1, 2, 3]])
assert oh.get_params()['categories'] == [[0, 1, 2, 3]]
assert oh.fit_transform(X).toarray().shape == (2, 4)
# set params on already fitted object
oh.set_params(categories=[[0, 1, 2, 3, 4]])
assert oh.fit_transform(X).toarray().shape == (2, 5)
def test_one_hot_encoder_feature_names():
enc = OneHotEncoder()
X = [['Male', 1, 'girl', 2, 3], ['Female', 41, 'girl', 1, 10],
['Male', 51, 'boy', 12, 3], ['Male', 91, 'girl', 21, 30]]
enc.fit(X)
feature_names = enc.get_feature_names()
assert isinstance(feature_names, np.ndarray)
assert_array_equal([
'x0_Female', 'x0_Male', 'x1_1', 'x1_41', 'x1_51', 'x1_91', 'x2_boy',
'x2_girl', 'x3_1', 'x3_2', 'x3_12', 'x3_21', 'x4_3', 'x4_10', 'x4_30'
], feature_names)
feature_names2 = enc.get_feature_names(
['one', 'two', 'three', 'four', 'five'])
assert_array_equal([
'one_Female', 'one_Male', 'two_1', 'two_41', 'two_51', 'two_91',
'three_boy', 'three_girl', 'four_1', 'four_2', 'four_12', 'four_21',
'five_3', 'five_10', 'five_30'
], feature_names2)
with pytest.raises(ValueError, match="input_features should have length"):
enc.get_feature_names(['one', 'two'])
def test_one_hot_encoder_handle_unknown_strings():
X = np.array(['11111111', '22', '333', '4444']).reshape((-1, 1))
X2 = np.array(['55555', '22']).reshape((-1, 1))
# Non Regression test for the issue #12470
# Test the ignore option, when categories are numpy string dtype
# particularly when the known category strings are larger
# than the unknown category strings
oh = OneHotEncoder(handle_unknown='ignore')
oh.fit(X)
X2_passed = X2.copy()
assert_array_equal(
oh.transform(X2_passed).toarray(),
np.array([[0., 0., 0., 0.], [0., 1., 0., 0.]]))
# ensure transformed data was not modified in place
assert_array_equal(X2, X2_passed)
def test_permutation_importance_mixed_types_pandas():
pd = pytest.importorskip("pandas")
rng = np.random.RandomState(42)
n_repeats = 5
# Last column is correlated with y
X = pd.DataFrame({
'col1': [1.0, 2.0, 3.0, np.nan],
'col2': ['a', 'b', 'a', 'b']
})
y = np.array([0, 1, 0, 1])
num_preprocess = make_pipeline(SimpleImputer(), StandardScaler())
preprocess = ColumnTransformer([('num', num_preprocess, ['col1']),
('cat', OneHotEncoder(), ['col2'])])
clf = make_pipeline(preprocess, LogisticRegression(solver='lbfgs'))
clf.fit(X, y)
result = permutation_importance(clf,
X,
y,
n_repeats=n_repeats,
random_state=rng)
assert result.importances.shape == (X.shape[1], n_repeats)
# the correlated feature with y is the last column and should
# have the highest importance
assert np.all(result.importances_mean[-1] > result.importances_mean[:-1])
def test_encode_options():
est = KBinsDiscretizer(n_bins=[2, 3, 3, 3], encode='ordinal').fit(X)
Xt_1 = est.transform(X)
est = KBinsDiscretizer(n_bins=[2, 3, 3, 3], encode='onehot-dense').fit(X)
Xt_2 = est.transform(X)
assert not sp.issparse(Xt_2)
assert_array_equal(
OneHotEncoder(categories=[np.arange(i) for i in [2, 3, 3, 3]],
sparse=False).fit_transform(Xt_1), Xt_2)
est = KBinsDiscretizer(n_bins=[2, 3, 3, 3], encode='onehot').fit(X)
Xt_3 = est.transform(X)
assert sp.issparse(Xt_3)
assert_array_equal(
OneHotEncoder(categories=[np.arange(i) for i in [2, 3, 3, 3]],
sparse=True).fit_transform(Xt_1).toarray(),
Xt_3.toarray())
def test_X_is_not_1D_pandas(method):
pd = pytest.importorskip('pandas')
X = pd.Series([6, 3, 4, 6])
oh = OneHotEncoder()
msg = ("Expected 2D array, got 1D array instead")
with pytest.raises(ValueError, match=msg):
getattr(oh, method)(X)
def test_one_hot_encoder_specified_categories(X, X2, cats, cat_dtype):
enc = OneHotEncoder(categories=cats)
exp = np.array([[1., 0., 0.], [0., 1., 0.]])
assert_array_equal(enc.fit_transform(X).toarray(), exp)
assert list(enc.categories[0]) == list(cats[0])
assert enc.categories_[0].tolist() == list(cats[0])
# manually specified categories should have same dtype as
# the data when coerced from lists
assert enc.categories_[0].dtype == cat_dtype
# when specifying categories manually, unknown categories should already
# raise when fitting
enc = OneHotEncoder(categories=cats)
with pytest.raises(ValueError, match="Found unknown categories"):
enc.fit(X2)
enc = OneHotEncoder(categories=cats, handle_unknown='ignore')
exp = np.array([[1., 0., 0.], [0., 0., 0.]])
assert_array_equal(enc.fit(X2).transform(X2).toarray(), exp)
def test_one_hot_encoder_dtype(input_dtype, output_dtype):
X = np.asarray([[0, 1]], dtype=input_dtype).T
X_expected = np.asarray([[1, 0], [0, 1]], dtype=output_dtype)
oh = OneHotEncoder(categories='auto', dtype=output_dtype)
assert_array_equal(oh.fit_transform(X).toarray(), X_expected)
assert_array_equal(oh.fit(X).transform(X).toarray(), X_expected)
oh = OneHotEncoder(categories='auto', dtype=output_dtype, sparse=False)
assert_array_equal(oh.fit_transform(X), X_expected)
assert_array_equal(oh.fit(X).transform(X), X_expected)
def test_column_transformer_negative_column_indexes():
X = np.random.randn(2, 2)
X_categories = np.array([[1], [2]])
X = np.concatenate([X, X_categories], axis=1)
ohe = OneHotEncoder()
tf_1 = ColumnTransformer([('ohe', ohe, [-1])], remainder='passthrough')
tf_2 = ColumnTransformer([('ohe', ohe, [2])], remainder='passthrough')
assert_array_equal(tf_1.fit_transform(X), tf_2.fit_transform(X))
def test_one_hot_encoder_dtype_pandas(output_dtype):
pd = pytest.importorskip('pandas')
X_df = pd.DataFrame({'A': ['a', 'b'], 'B': [1, 2]})
X_expected = np.array([[1, 0, 1, 0], [0, 1, 0, 1]], dtype=output_dtype)
oh = OneHotEncoder(dtype=output_dtype)
assert_array_equal(oh.fit_transform(X_df).toarray(), X_expected)
assert_array_equal(oh.fit(X_df).transform(X_df).toarray(), X_expected)
oh = OneHotEncoder(dtype=output_dtype, sparse=False)
assert_array_equal(oh.fit_transform(X_df), X_expected)
assert_array_equal(oh.fit(X_df).transform(X_df), X_expected)
def test_column_transformer_mixed_cols_sparse():
df = np.array([['a', 1, True], ['b', 2, False]], dtype='O')
ct = make_column_transformer((OneHotEncoder(), [0]),
('passthrough', [1, 2]),
sparse_threshold=1.0)
# this shouldn't fail, since boolean can be coerced into a numeric
# See: https://github.com/scikit-learn/scikit-learn/issues/11912
X_trans = ct.fit_transform(df)
assert X_trans.getformat() == 'csr'
assert_array_equal(X_trans.toarray(), np.array([[1, 0, 1, 1], [0, 1, 2,
0]]))
ct = make_column_transformer((OneHotEncoder(), [0]), ('passthrough', [0]),
sparse_threshold=1.0)
with pytest.raises(ValueError,
match="For a sparse output, all columns should"):
# this fails since strings `a` and `b` cannot be
# coerced into a numeric.
ct.fit_transform(df)
def test_one_hot_encoder_raise_missing(X, as_data_frame, handle_unknown):
if as_data_frame:
pd = pytest.importorskip('pandas')
X = pd.DataFrame(X)
ohe = OneHotEncoder(categories='auto', handle_unknown=handle_unknown)
with pytest.raises(ValueError, match="Input contains NaN"):
ohe.fit(X)
with pytest.raises(ValueError, match="Input contains NaN"):
ohe.fit_transform(X)
if as_data_frame:
X_partial = X.iloc[:1, :]
else:
X_partial = X[:1, :]
ohe.fit(X_partial)
with pytest.raises(ValueError, match="Input contains NaN"):
ohe.transform(X)
def test_categories(density, drop):
ohe_base = OneHotEncoder(sparse=density)
ohe_test = OneHotEncoder(sparse=density, drop=drop)
X = [['c', 1, 'a'], ['a', 2, 'b']]
ohe_base.fit(X)
ohe_test.fit(X)
assert_array_equal(ohe_base.categories_, ohe_test.categories_)
if drop == 'first':
assert_array_equal(ohe_test.drop_idx_, 0)
else:
for drop_cat, drop_idx, cat_list in zip(drop, ohe_test.drop_idx_,
ohe_test.categories_):
assert cat_list[drop_idx] == drop_cat
assert isinstance(ohe_test.drop_idx_, np.ndarray)
assert ohe_test.drop_idx_.dtype == np.int_
def test_one_hot_encoder_feature_names_unicode():
enc = OneHotEncoder()
X = np.array([['c❤t1', 'dat2']], dtype=object).T
enc.fit(X)
feature_names = enc.get_feature_names()
assert_array_equal(['x0_c❤t1', 'x0_dat2'], feature_names)
feature_names = enc.get_feature_names(input_features=['n👍me'])
assert_array_equal(['n👍me_c❤t1', 'n👍me_dat2'], feature_names)
def test_column_transformer_list():
X_list = [[1, float('nan'), 'a'], [0, 0, 'b']]
expected_result = np.array([
[1, float('nan'), 1, 0],
[-1, 0, 0, 1],
])
ct = ColumnTransformer([
('numerical', StandardScaler(), [0, 1]),
('categorical', OneHotEncoder(), [2]),
])
assert_array_equal(ct.fit_transform(X_list), expected_result)
assert_array_equal(ct.fit(X_list).transform(X_list), expected_result)
def test_one_hot_encoder_unsorted_categories():
X = np.array([['a', 'b']], dtype=object).T
enc = OneHotEncoder(categories=[['b', 'a', 'c']])
exp = np.array([[0., 1., 0.], [1., 0., 0.]])
assert_array_equal(enc.fit(X).transform(X).toarray(), exp)
assert_array_equal(enc.fit_transform(X).toarray(), exp)
assert enc.categories_[0].tolist() == ['b', 'a', 'c']
assert np.issubdtype(enc.categories_[0].dtype, np.object_)
# unsorted passed categories still raise for numerical values
X = np.array([[1, 2]]).T
enc = OneHotEncoder(categories=[[2, 1, 3]])
msg = 'Unsorted categories are not supported'
with pytest.raises(ValueError, match=msg):
enc.fit_transform(X)
def test_one_hot_encoder_diff_n_features():
X = np.array([[0, 2, 1], [1, 0, 3], [1, 0, 2]])
X2 = np.array([[1, 0]])
enc = OneHotEncoder()
enc.fit(X)
err_msg = ("The number of features in X is different to the number of "
"features of the fitted data.")
with pytest.raises(ValueError, match=err_msg):
enc.transform(X2)
def test_encoder_dtypes_pandas():
# check dtype (similar to test_categorical_encoder_dtypes for dataframes)
pd = pytest.importorskip('pandas')
enc = OneHotEncoder(categories='auto')
exp = np.array([[1., 0., 1., 0., 1., 0.], [0., 1., 0., 1., 0., 1.]],
dtype='float64')
X = pd.DataFrame({'A': [1, 2], 'B': [3, 4], 'C': [5, 6]}, dtype='int64')
enc.fit(X)
assert all([enc.categories_[i].dtype == 'int64' for i in range(2)])
assert_array_equal(enc.transform(X).toarray(), exp)
X = pd.DataFrame({'A': [1, 2], 'B': ['a', 'b'], 'C': [3., 4.]})
X_type = [X['A'].dtype, X['B'].dtype, X['C'].dtype]
enc.fit(X)
assert all([enc.categories_[i].dtype == X_type[i] for i in range(3)])
assert_array_equal(enc.transform(X).toarray(), exp)
def check_categorical_onehot(X):
enc = OneHotEncoder(categories='auto')
Xtr1 = enc.fit_transform(X)
enc = OneHotEncoder(categories='auto', sparse=False)
Xtr2 = enc.fit_transform(X)
assert_allclose(Xtr1.toarray(), Xtr2)
assert sparse.isspmatrix_csr(Xtr1)
return Xtr1.toarray()
def test_column_transformer_sparse_threshold():
X_array = np.array([['a', 'b'], ['A', 'B']], dtype=object).T
# above data has sparsity of 4 / 8 = 0.5
# apply threshold even if all sparse
col_trans = ColumnTransformer([('trans1', OneHotEncoder(), [0]),
('trans2', OneHotEncoder(), [1])],
sparse_threshold=0.2)
res = col_trans.fit_transform(X_array)
assert not sparse.issparse(res)
assert not col_trans.sparse_output_
# mixed -> sparsity of (4 + 2) / 8 = 0.75
for thres in [0.75001, 1]:
col_trans = ColumnTransformer(
[('trans1', OneHotEncoder(sparse=True), [0]),
('trans2', OneHotEncoder(sparse=False), [1])],
sparse_threshold=thres)
res = col_trans.fit_transform(X_array)
assert sparse.issparse(res)
assert col_trans.sparse_output_
for thres in [0.75, 0]:
col_trans = ColumnTransformer(
[('trans1', OneHotEncoder(sparse=True), [0]),
('trans2', OneHotEncoder(sparse=False), [1])],
sparse_threshold=thres)
res = col_trans.fit_transform(X_array)
assert not sparse.issparse(res)
assert not col_trans.sparse_output_
# if nothing is sparse -> no sparse
for thres in [0.33, 0, 1]:
col_trans = ColumnTransformer(
[('trans1', OneHotEncoder(sparse=False), [0]),
('trans2', OneHotEncoder(sparse=False), [1])],
sparse_threshold=thres)
res = col_trans.fit_transform(X_array)
assert not sparse.issparse(res)
assert not col_trans.sparse_output_
def test_one_hot_encoder_sparse_dense():
# check that sparse and dense will give the same results
X = np.array([[3, 2, 1], [0, 1, 1]])
enc_sparse = OneHotEncoder()
enc_dense = OneHotEncoder(sparse=False)
X_trans_sparse = enc_sparse.fit_transform(X)
X_trans_dense = enc_dense.fit_transform(X)
assert X_trans_sparse.shape == (2, 5)
assert X_trans_dense.shape == (2, 5)
assert sparse.issparse(X_trans_sparse)
assert not sparse.issparse(X_trans_dense)
# check outcome
assert_array_equal(X_trans_sparse.toarray(),
[[0., 1., 0., 1., 1.], [1., 0., 1., 0., 1.]])
assert_array_equal(X_trans_sparse.toarray(), X_trans_dense)
def test_invalid_drop_length(drop):
enc = OneHotEncoder(drop=drop)
err_msg = "`drop` should have length equal to the number"
with pytest.raises(ValueError, match=err_msg):
enc.fit([['abc', 2, 55], ['def', 1, 55], ['def', 3, 59]])
test_size=0.5)
# Unsupervised transformation based on totally random trees
rt = RandomTreesEmbedding(max_depth=3,
n_estimators=n_estimator,
random_state=0)
rt_lm = LogisticRegression(max_iter=1000)
pipeline = make_pipeline(rt, rt_lm)
pipeline.fit(X_train, y_train)
y_pred_rt = pipeline.predict_proba(X_test)[:, 1]
fpr_rt_lm, tpr_rt_lm, _ = roc_curve(y_test, y_pred_rt)
# Supervised transformation based on random forests
rf = RandomForestClassifier(max_depth=3, n_estimators=n_estimator)
rf_enc = OneHotEncoder()
rf_lm = LogisticRegression(max_iter=1000)
rf.fit(X_train, y_train)
rf_enc.fit(rf.apply(X_train))
rf_lm.fit(rf_enc.transform(rf.apply(X_train_lr)), y_train_lr)
y_pred_rf_lm = rf_lm.predict_proba(rf_enc.transform(rf.apply(X_test)))[:, 1]
fpr_rf_lm, tpr_rf_lm, _ = roc_curve(y_test, y_pred_rf_lm)
# Supervised transformation based on gradient boosted trees
grd = GradientBoostingClassifier(n_estimators=n_estimator)
grd_enc = OneHotEncoder()
grd_lm = LogisticRegression(max_iter=1000)
grd.fit(X_train, y_train)
grd_enc.fit(grd.apply(X_train)[:, :, 0])
grd_lm.fit(grd_enc.transform(grd.apply(X_train_lr)[:, :, 0]), y_train_lr)
# - fare: float.
# Categorical Features:
# - embarked: categories encoded as strings {'C', 'S', 'Q'}.
# - sex: categories encoded as strings {'female', 'male'}.
# - pclass: ordinal integers {1, 2, 3}.
# We create the preprocessing pipelines for both numeric and categorical data.
numeric_features = ['age', 'fare']
numeric_transformer = Pipeline(
steps=[('imputer',
SimpleImputer(strategy='median')), ('scaler', StandardScaler())])
categorical_features = ['embarked', 'sex', 'pclass']
categorical_transformer = Pipeline(
steps=[('imputer', SimpleImputer(strategy='constant', fill_value='missing')
), ('onehot', OneHotEncoder(handle_unknown='ignore'))])
preprocessor = ColumnTransformer(transformers=[(
'num', numeric_transformer,
numeric_features), ('cat', categorical_transformer, categorical_features)])
# Append classifier to preprocessing pipeline.
# Now we have a full prediction pipeline.
clf = Pipeline(steps=[('preprocessor',
preprocessor), ('classifier', LogisticRegression())])
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2)
clf.fit(X_train, y_train)
print("model score: %.3f" % clf.score(X_test, y_test))
