scikit-learn/sklearn/ensemble/tests/test_gradient_boosting.py

601 lines
21 KiB
Python

"""
Testing for the gradient boosting module (sklearn.ensemble.gradient_boosting).
"""
import numpy as np
import warnings
from sklearn.utils.testing import assert_equal
from sklearn.utils.testing import assert_array_equal
from sklearn.utils.testing import assert_array_almost_equal
from sklearn.utils.testing import assert_raises
from sklearn.utils.testing import assert_true
from sklearn.metrics import mean_squared_error
from sklearn.utils import check_random_state, tosequence
from sklearn.utils.validation import DataConversionWarning
from sklearn.ensemble import GradientBoostingClassifier
from sklearn.ensemble import GradientBoostingRegressor
from sklearn import datasets
# toy sample
X = [[-2, -1], [-1, -1], [-1, -2], [1, 1], [1, 2], [2, 1]]
y = [-1, -1, -1, 1, 1, 1]
T = [[-1, -1], [2, 2], [3, 2]]
true_result = [-1, 1, 1]
rng = np.random.RandomState(0)
# also load the boston dataset
# and randomly permute it
boston = datasets.load_boston()
perm = rng.permutation(boston.target.size)
boston.data = boston.data[perm]
boston.target = boston.target[perm]
# also load the iris dataset
# and randomly permute it
iris = datasets.load_iris()
perm = rng.permutation(iris.target.size)
iris.data = iris.data[perm]
iris.target = iris.target[perm]
def test_classification_toy():
"""Check classification on a toy dataset."""
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
assert_raises(ValueError, clf.predict, T)
clf.fit(X, y)
assert_array_equal(clf.predict(T), true_result)
assert_equal(100, len(clf.estimators_))
deviance_decrease = (clf.train_score_[:-1] - clf.train_score_[1:])
assert np.any(deviance_decrease >= 0.0), \
"Train deviance does not monotonically decrease."
def test_parameter_checks():
"""Check input parameter validation."""
assert_raises(ValueError,
GradientBoostingClassifier(n_estimators=0).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(n_estimators=-1).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(learning_rate=0.0).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(learning_rate=-1.0).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(loss='foobar').fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(min_samples_split=0.0).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(min_samples_split=-1.0).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(min_samples_leaf=0).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(min_samples_leaf=-1.).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(subsample=0.0).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(subsample=1.1).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(subsample=-0.1).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(max_depth=-0.1).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(max_depth=0).fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(init={}).fit, X, y)
# test fit before feature importance
assert_raises(ValueError,
lambda: GradientBoostingClassifier().feature_importances_)
# deviance requires ``n_classes >= 2``.
assert_raises(ValueError,
lambda X, y: GradientBoostingClassifier(
loss='deviance').fit(X, y),
X, [0, 0, 0, 0])
def test_loss_function():
assert_raises(ValueError,
GradientBoostingClassifier(loss='ls').fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(loss='lad').fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(loss='quantile').fit, X, y)
assert_raises(ValueError,
GradientBoostingClassifier(loss='huber').fit, X, y)
assert_raises(ValueError,
GradientBoostingRegressor(loss='deviance').fit, X, y)
def test_classification_synthetic():
"""Test GradientBoostingClassifier on synthetic dataset used by
Hastie et al. in ESLII Example 12.7. """
X, y = datasets.make_hastie_10_2(n_samples=12000, random_state=1)
X_train, X_test = X[:2000], X[2000:]
y_train, y_test = y[:2000], y[2000:]
gbrt = GradientBoostingClassifier(n_estimators=100, min_samples_split=1,
max_depth=1,
learning_rate=1.0, random_state=0)
gbrt.fit(X_train, y_train)
error_rate = (1.0 - gbrt.score(X_test, y_test))
assert error_rate < 0.085, \
"GB failed with error %.4f" % error_rate
gbrt = GradientBoostingClassifier(n_estimators=200, min_samples_split=1,
max_depth=1,
learning_rate=1.0, subsample=0.5,
random_state=0)
gbrt.fit(X_train, y_train)
error_rate = (1.0 - gbrt.score(X_test, y_test))
assert error_rate < 0.08, \
"Stochastic GB failed with error %.4f" % error_rate
def test_boston():
"""Check consistency on dataset boston house prices with least squares
and least absolute deviation. """
for loss in ("ls", "lad", "huber"):
clf = GradientBoostingRegressor(n_estimators=100, loss=loss,
max_depth=4,
min_samples_split=1, random_state=1)
assert_raises(ValueError, clf.predict, boston.data)
clf.fit(boston.data, boston.target)
y_pred = clf.predict(boston.data)
mse = mean_squared_error(boston.target, y_pred)
assert mse < 6.0, "Failed with loss %s and mse = %.4f" % (loss, mse)
def test_iris():
"""Check consistency on dataset iris."""
for subsample in (1.0, 0.5):
clf = GradientBoostingClassifier(n_estimators=100, loss='deviance',
random_state=1, subsample=subsample)
clf.fit(iris.data, iris.target)
score = clf.score(iris.data, iris.target)
assert score > 0.9, "Failed with subsample %.1f " \
"and score = %f" % (subsample, score)
def test_regression_synthetic():
"""Test on synthetic regression datasets used in Leo Breiman,
`Bagging Predictors?. Machine Learning 24(2): 123-140 (1996). """
random_state = check_random_state(1)
regression_params = {'n_estimators': 100, 'max_depth': 4,
'min_samples_split': 1, 'learning_rate': 0.1,
'loss': 'ls'}
# Friedman1
X, y = datasets.make_friedman1(n_samples=1200,
random_state=random_state, noise=1.0)
X_train, y_train = X[:200], y[:200]
X_test, y_test = X[200:], y[200:]
clf = GradientBoostingRegressor()
clf.fit(X_train, y_train)
mse = mean_squared_error(y_test, clf.predict(X_test))
assert mse < 5.0, "Failed on Friedman1 with mse = %.4f" % mse
# Friedman2
X, y = datasets.make_friedman2(n_samples=1200, random_state=random_state)
X_train, y_train = X[:200], y[:200]
X_test, y_test = X[200:], y[200:]
clf = GradientBoostingRegressor(**regression_params)
clf.fit(X_train, y_train)
mse = mean_squared_error(y_test, clf.predict(X_test))
assert mse < 1700.0, "Failed on Friedman2 with mse = %.4f" % mse
# Friedman3
X, y = datasets.make_friedman3(n_samples=1200, random_state=random_state)
X_train, y_train = X[:200], y[:200]
X_test, y_test = X[200:], y[200:]
clf = GradientBoostingRegressor(**regression_params)
clf.fit(X_train, y_train)
mse = mean_squared_error(y_test, clf.predict(X_test))
assert mse < 0.015, "Failed on Friedman3 with mse = %.4f" % mse
def test_feature_importances():
X = np.array(boston.data, dtype=np.float32)
y = np.array(boston.target, dtype=np.float32)
clf = GradientBoostingRegressor(n_estimators=100, max_depth=5,
min_samples_split=1, random_state=1)
clf.fit(X, y)
#feature_importances = clf.feature_importances_
assert_true(hasattr(clf, 'feature_importances_'))
# true feature importance ranking
# true_ranking = np.array([3, 1, 8, 2, 10, 9, 4, 11, 0, 6, 7, 5, 12])
# assert_array_equal(true_ranking, feature_importances.argsort())
def test_probability():
"""Predict probabilities."""
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
assert_raises(ValueError, clf.predict_proba, T)
clf.fit(X, y)
assert_array_equal(clf.predict(T), true_result)
# check if probabilities are in [0, 1].
y_proba = clf.predict_proba(T)
assert np.all(y_proba >= 0.0)
assert np.all(y_proba <= 1.0)
# derive predictions from probabilities
y_pred = clf.classes_.take(y_proba.argmax(axis=1), axis=0)
assert_array_equal(y_pred, true_result)
def test_check_inputs():
"""Test input checks (shape and type of X and y)."""
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
assert_raises(ValueError, clf.fit, X, y + [0, 1])
from scipy import sparse
X_sparse = sparse.csr_matrix(X)
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
assert_raises(TypeError, clf.fit, X_sparse, y)
clf = GradientBoostingClassifier().fit(X, y)
assert_raises(TypeError, clf.predict, X_sparse)
def test_check_inputs_predict():
"""X has wrong shape """
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
clf.fit(X, y)
x = np.array([1.0, 2.0])[:, np.newaxis]
assert_raises(ValueError, clf.predict, x)
x = np.array([])
assert_raises(ValueError, clf.predict, x)
x = np.array([1.0, 2.0, 3.0])[:, np.newaxis]
assert_raises(ValueError, clf.predict, x)
clf = GradientBoostingRegressor(n_estimators=100, random_state=1)
clf.fit(X, rng.rand(len(X)))
x = np.array([1.0, 2.0])[:, np.newaxis]
assert_raises(ValueError, clf.predict, x)
x = np.array([])
assert_raises(ValueError, clf.predict, x)
x = np.array([1.0, 2.0, 3.0])[:, np.newaxis]
assert_raises(ValueError, clf.predict, x)
def test_check_max_features():
"""test if max_features is valid. """
clf = GradientBoostingRegressor(n_estimators=100, random_state=1,
max_features=0)
assert_raises(ValueError, clf.fit, X, y)
clf = GradientBoostingRegressor(n_estimators=100, random_state=1,
max_features=(len(X[0]) + 1))
assert_raises(ValueError, clf.fit, X, y)
def test_max_feature_regression():
"""Test to make sure random state is set properly. """
X, y = datasets.make_hastie_10_2(n_samples=12000, random_state=1)
X_train, X_test = X[:2000], X[2000:]
y_train, y_test = y[:2000], y[2000:]
gbrt = GradientBoostingClassifier(n_estimators=100, min_samples_split=5,
max_depth=2, learning_rate=.1,
max_features=2, random_state=1)
gbrt.fit(X_train, y_train)
deviance = gbrt.loss_(y_test, gbrt.decision_function(X_test))
assert_true(deviance < 0.5, "GB failed with deviance %.4f" % deviance)
def test_staged_predict():
"""Test whether staged decision function eventually gives
the same prediction.
"""
X, y = datasets.make_friedman1(n_samples=1200,
random_state=1, noise=1.0)
X_train, y_train = X[:200], y[:200]
X_test, y_test = X[200:], y[200:]
clf = GradientBoostingRegressor()
# test raise ValueError if not fitted
assert_raises(ValueError, lambda X: np.fromiter(
clf.staged_predict(X), dtype=np.float64), X_test)
clf.fit(X_train, y_train)
y_pred = clf.predict(X_test)
# test if prediction for last stage equals ``predict``
for y in clf.staged_predict(X_test):
assert_equal(y.shape, y_pred.shape)
assert_array_equal(y_pred, y)
def test_staged_predict_proba():
"""Test whether staged predict proba eventually gives
the same prediction.
"""
X, y = datasets.make_hastie_10_2(n_samples=1200,
random_state=1)
X_train, y_train = X[:200], y[:200]
X_test, y_test = X[200:], y[200:]
clf = GradientBoostingClassifier(n_estimators=20)
# test raise ValueError if not fitted
assert_raises(ValueError, lambda X: np.fromiter(
clf.staged_predict_proba(X), dtype=np.float64), X_test)
clf.fit(X_train, y_train)
# test if prediction for last stage equals ``predict``
for y_pred in clf.staged_predict(X_test):
assert_equal(y_test.shape, y_pred.shape)
assert_array_equal(clf.predict(X_test), y_pred)
# test if prediction for last stage equals ``predict_proba``
for staged_proba in clf.staged_predict_proba(X_test):
assert_equal(y_test.shape[0], staged_proba.shape[0])
assert_equal(2, staged_proba.shape[1])
assert_array_equal(clf.predict_proba(X_test), staged_proba)
def test_serialization():
"""Check model serialization."""
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
clf.fit(X, y)
assert_array_equal(clf.predict(T), true_result)
assert_equal(100, len(clf.estimators_))
try:
import cPickle as pickle
except ImportError:
import pickle
serialized_clf = pickle.dumps(clf, protocol=pickle.HIGHEST_PROTOCOL)
clf = None
clf = pickle.loads(serialized_clf)
assert_array_equal(clf.predict(T), true_result)
assert_equal(100, len(clf.estimators_))
def test_degenerate_targets():
"""Check if we can fit even though all targets are equal. """
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
# classifier should raise exception
assert_raises(ValueError, clf.fit, X, np.ones(len(X)))
clf = GradientBoostingRegressor(n_estimators=100, random_state=1)
clf.fit(X, np.ones(len(X)))
clf.predict(rng.rand(2))
assert_array_equal(np.ones((1,), dtype=np.float64),
clf.predict(rng.rand(2)))
def test_quantile_loss():
"""Check if quantile loss with alpha=0.5 equals lad. """
clf_quantile = GradientBoostingRegressor(n_estimators=100, loss='quantile',
max_depth=4, alpha=0.5,
random_state=7)
clf_quantile.fit(boston.data, boston.target)
y_quantile = clf_quantile.predict(boston.data)
clf_lad = GradientBoostingRegressor(n_estimators=100, loss='lad',
max_depth=4, random_state=7)
clf_lad.fit(boston.data, boston.target)
y_lad = clf_lad.predict(boston.data)
assert_array_almost_equal(y_quantile, y_lad, decimal=4)
def test_symbol_labels():
"""Test with non-integer class labels. """
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
symbol_y = tosequence(map(str, y))
clf.fit(X, symbol_y)
assert_array_equal(clf.predict(T), tosequence(map(str, true_result)))
assert_equal(100, len(clf.estimators_))
def test_float_class_labels():
"""Test with float class labels. """
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
float_y = np.asarray(y, dtype=np.float32)
clf.fit(X, float_y)
assert_array_equal(clf.predict(T),
np.asarray(true_result, dtype=np.float32))
assert_equal(100, len(clf.estimators_))
def test_shape_y():
"""Test with float class labels. """
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
y_ = np.asarray(y, dtype=np.int32)
y_ = y_[:, np.newaxis]
with warnings.catch_warnings(record=True):
# This will raise a DataConversionWarning that we want to
# "always" raise, elsewhere the warnings gets ignored in the
# later tests, and the tests that check for this warning fail
warnings.simplefilter("always", DataConversionWarning)
clf.fit(X, y_)
assert_array_equal(clf.predict(T), true_result)
assert_equal(100, len(clf.estimators_))
def test_mem_layout():
"""Test with different memory layouts of X and y"""
X_ = np.asfortranarray(X)
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
clf.fit(X_, y)
assert_array_equal(clf.predict(T), true_result)
assert_equal(100, len(clf.estimators_))
X_ = np.ascontiguousarray(X)
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
clf.fit(X_, y)
assert_array_equal(clf.predict(T), true_result)
assert_equal(100, len(clf.estimators_))
y_ = np.asarray(y, dtype=np.int32)
y_ = np.ascontiguousarray(y_)
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
clf.fit(X, y_)
assert_array_equal(clf.predict(T), true_result)
assert_equal(100, len(clf.estimators_))
y_ = np.asarray(y, dtype=np.int32)
y_ = np.asfortranarray(y_)
clf = GradientBoostingClassifier(n_estimators=100, random_state=1)
clf.fit(X, y_)
assert_array_equal(clf.predict(T), true_result)
assert_equal(100, len(clf.estimators_))
def test_oob_score():
"""Test if oob_score is deprecated. """
clf = GradientBoostingClassifier(n_estimators=100, random_state=1,
subsample=0.5)
clf.fit(X, y)
with warnings.catch_warnings(record=True) as w:
warnings.simplefilter("always")
assert_true(hasattr(clf, 'oob_score_'))
assert_equal(len(w), 1)
def test_oob_improvement():
"""Test if oob improvement has correct shape and regression test. """
clf = GradientBoostingClassifier(n_estimators=100, random_state=1,
subsample=0.5)
clf.fit(X, y)
assert clf.oob_improvement_.shape[0] == 100
# hard-coded regression test - change if modification in OOB computation
assert_array_almost_equal(clf.oob_improvement_[:5],
np.array([0.19, 0.15, 0.12, -0.12, -0.11]),
decimal=2)
def test_oob_improvement_raise():
"""Test if oob improvement has correct shape. """
clf = GradientBoostingClassifier(n_estimators=100, random_state=1,
subsample=1.0)
clf.fit(X, y)
assert_raises(AttributeError, lambda: clf.oob_improvement_)
def test_oob_multilcass_iris():
"""Check OOB improvement on multi-class dataset."""
clf = GradientBoostingClassifier(n_estimators=100, loss='deviance',
random_state=1, subsample=0.5)
clf.fit(iris.data, iris.target)
score = clf.score(iris.data, iris.target)
assert score > 0.9, "Failed with subsample %.1f " \
"and score = %f" % (0.5, score)
assert clf.oob_improvement_.shape[0] == clf.n_estimators
# hard-coded regression test - change if modification in OOB computation
# FIXME: the following snippet does not yield the same results on 32 bits
# assert_array_almost_equal(clf.oob_improvement_[:5],
# np.array([12.68, 10.45, 8.18, 6.43, 5.13]),
# decimal=2)
def test_verbose_output():
"""Check verbose=1 does not cause error. """
from sklearn.externals.six.moves import cStringIO as StringIO
import sys
old_stdout = sys.stdout
sys.stdout = StringIO()
clf = GradientBoostingClassifier(n_estimators=100, random_state=1,
verbose=1, subsample=0.8)
clf.fit(X, y)
verbose_output = sys.stdout
sys.stdout = old_stdout
# check output
verbose_output.seek(0)
header = verbose_output.readline().rstrip()
# with OOB
true_header = ' '.join(['%10s'] + ['%16s'] * 3) % (
'Iter', 'Train Loss', 'OOB Improve', 'Remaining Time')
assert_equal(true_header, header)
n_lines = sum(1 for l in verbose_output.readlines())
# one for 1-10 and then 9 for 20-100
assert_equal(10 + 9, n_lines)
def test_more_verbose_output():
"""Check verbose=2 does not cause error. """
from sklearn.externals.six.moves import cStringIO as StringIO
import sys
old_stdout = sys.stdout
sys.stdout = StringIO()
clf = GradientBoostingClassifier(n_estimators=100, random_state=1,
verbose=2)
clf.fit(X, y)
verbose_output = sys.stdout
sys.stdout = old_stdout
# check output
verbose_output.seek(0)
header = verbose_output.readline().rstrip()
# no OOB
true_header = ' '.join(['%10s'] + ['%16s'] * 2) % (
'Iter', 'Train Loss', 'Remaining Time')
assert_equal(true_header, header)
n_lines = sum(1 for l in verbose_output.readlines())
# 100 lines for n_estimators==100
assert_equal(100, n_lines)
def test_warn_deviance():
"""Test if mdeviance and bdeviance give deprecated warning. """
for loss in ('bdeviance', 'mdeviance'):
with warnings.catch_warnings(record=True) as w:
# This will raise a DataConversionWarning that we want to
# "always" raise, elsewhere the warnings gets ignored in the
# later tests, and the tests that check for this warning fail
warnings.simplefilter("always", DataConversionWarning)
clf = GradientBoostingClassifier(loss=loss)
try:
clf.fit(X, y)
except:
# mdeviance will raise ValueError because only 2 classes
pass
# deprecated warning for bdeviance and mdeviance
assert len(w) == 1