# Out-of-fold stacking regressor tests
#
# Sebastian Raschka 2014-2023
#
# mlxtend Machine Learning Library Extensions
# Author: Eike Dehling <e.e.dehling@gmail.com>
#
# License: BSD 3 clause

import random

import numpy as np
import pytest
from packaging.version import Version
from scipy import sparse
from sklearn import __version__ as sklearn_version
from sklearn.base import clone
from sklearn.linear_model import Lasso, LinearRegression, Ridge
from sklearn.model_selection import GridSearchCV, KFold, train_test_split
from sklearn.neighbors import KNeighborsRegressor
from sklearn.svm import SVR

from mlxtend.externals.estimator_checks import NotFittedError
from mlxtend.regressor import StackingCVRegressor
from mlxtend.utils import assert_raises

# Some test data
np.random.seed(1)
X1 = np.sort(5 * np.random.rand(40, 1), axis=0)
X2 = np.sort(5 * np.random.rand(40, 2), axis=0)
X3 = np.zeros((40, 3))
y = np.sin(X1).ravel()
y[::5] += 3 * (0.5 - np.random.rand(8))
y2 = np.sin(X2)
y3 = np.zeros((40,))


def test_different_models():
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, lr, ridge], meta_regressor=svr_rbf, random_state=0
    )
    stack.fit(X1, y).predict(X1)
    mse = 0.20
    got = np.mean((stack.predict(X1) - y) ** 2)
    assert round(got, 2) == mse, got


def test_use_features_in_secondary():
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, lr, ridge],
        meta_regressor=svr_rbf,
        cv=3,
        random_state=0,
        use_features_in_secondary=True,
    )
    stack.fit(X1, y).predict(X1)
    mse = 0.2
    got = np.mean((stack.predict(X1) - y) ** 2)
    assert round(got, 2) == mse, "%f != %f" % (round(got, 2), mse)


def test_multivariate():
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, lr, ridge], meta_regressor=svr_rbf, random_state=0
    )
    stack.fit(X2, y).predict(X2)
    mse = 0.20
    got = np.mean((stack.predict(X2) - y) ** 2)
    assert round(got, 2) == mse, "%f != %f" % (round(got, 2), mse)


def test_multivariate_class():
    lr = LinearRegression()
    ridge = Ridge(random_state=1)
    meta = LinearRegression()
    stregr = StackingCVRegressor(
        regressors=[lr, ridge], meta_regressor=meta, multi_output=True, random_state=0
    )
    stregr.fit(X2, y2).predict(X2)
    mse = 0.13
    got = np.mean((stregr.predict(X2) - y2) ** 2.0)
    assert round(got, 2) == mse, got


def test_internals():
    lr = LinearRegression()
    regressors = [lr, lr, lr, lr, lr]
    cv = 10
    stack = StackingCVRegressor(
        regressors=[lr, lr, lr, lr, lr], meta_regressor=lr, cv=cv, random_state=0
    )
    stack.fit(X3, y3)
    assert stack.predict(X3).mean() == y3.mean()
    assert stack.meta_regr_.intercept_ == 0.0
    assert stack.meta_regr_.coef_[0] == 0.0
    assert stack.meta_regr_.coef_[1] == 0.0
    assert stack.meta_regr_.coef_[2] == 0.0
    assert len(stack.regr_) == len(regressors)


def test_gridsearch_numerate_regr():
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, ridge, ridge], meta_regressor=svr_rbf, random_state=42
    )

    params = {
        "ridge-1__alpha": [0.01, 1.0],
        "ridge-2__alpha": [0.01, 1.0],
        "svr__C": [0.01, 1.0],
        "meta_regressor__C": [0.01, 1.0],
        "use_features_in_secondary": [True, False],
    }

    if Version(sklearn_version) < Version("0.24.1"):
        grid = GridSearchCV(
            estimator=stack, param_grid=params, cv=5, iid=False, refit=True, verbose=0
        )
    else:
        grid = GridSearchCV(
            estimator=stack, param_grid=params, cv=5, refit=True, verbose=0
        )
    grid = grid.fit(X1, y)
    got = round(grid.best_score_, 1)
    assert got >= 0.1 and got <= 0.2, "%f is wrong" % got


def test_get_params():
    lr = LinearRegression()
    svr_rbf = SVR(kernel="rbf")
    ridge = Ridge(random_state=1)
    stregr = StackingCVRegressor(
        regressors=[ridge, lr], meta_regressor=svr_rbf, random_state=42
    )

    got = sorted(list({s.split("__")[0] for s in stregr.get_params().keys()}))
    expect = [
        "cv",
        "linearregression",
        "meta_regressor",
        "multi_output",
        "n_jobs",
        "pre_dispatch",
        "random_state",
        "refit",
        "regressors",
        "ridge",
        "shuffle",
        "store_train_meta_features",
        "use_features_in_secondary",
        "verbose",
    ]
    assert got == expect, got


def test_regressor_gridsearch():
    lr = LinearRegression()
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    ridge = Ridge(random_state=1)
    stregr = StackingCVRegressor(
        regressors=[lr], meta_regressor=svr_rbf, random_state=1
    )

    params = {"regressors": [[ridge, lr], [lr, ridge, lr]]}

    if Version(sklearn_version) < Version("0.24.1"):
        grid = GridSearchCV(
            estimator=stregr, param_grid=params, iid=False, cv=5, refit=True
        )
    else:
        grid = GridSearchCV(estimator=stregr, param_grid=params, cv=5, refit=True)
    grid.fit(X1, y)

    assert len(grid.best_params_["regressors"]) == 3


def test_predict_meta_features():
    lr = LinearRegression()
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    ridge = Ridge(random_state=1)
    stregr = StackingCVRegressor(regressors=[lr, ridge], meta_regressor=svr_rbf)
    X_train, X_test, y_train, y_test = train_test_split(X2, y, test_size=0.3)
    stregr.fit(X_train, y_train)
    test_meta_features = stregr.predict(X_test)
    assert test_meta_features.shape[0] == X_test.shape[0]


def test_train_meta_features_():
    lr = LinearRegression()
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    ridge = Ridge(random_state=1)
    stregr = StackingCVRegressor(
        regressors=[lr, ridge], meta_regressor=svr_rbf, store_train_meta_features=True
    )
    X_train, X_test, y_train, y_test = train_test_split(X2, y, test_size=0.3)
    stregr.fit(X_train, y_train)
    train_meta_features = stregr.train_meta_features_
    assert train_meta_features.shape[0] == X_train.shape[0]


def test_not_fitted_predict():
    lr = LinearRegression()
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    ridge = Ridge(random_state=1)
    stregr = StackingCVRegressor(
        regressors=[lr, ridge], meta_regressor=svr_rbf, store_train_meta_features=True
    )
    X_train, X_test, y_train, y_test = train_test_split(X2, y, test_size=0.3)

    expect = (
        "This StackingCVRegressor instance is not fitted yet. Call "
        "'fit' with appropriate arguments before using this method."
    )

    assert_raises(NotFittedError, expect, stregr.predict, X_train)

    assert_raises(NotFittedError, expect, stregr.predict_meta_features, X_train)


def test_clone():
    lr = LinearRegression()
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    ridge = Ridge(random_state=1)
    stregr = StackingCVRegressor(
        regressors=[lr, ridge], meta_regressor=svr_rbf, store_train_meta_features=True
    )
    clone(stregr)


def test_sparse_matrix_inputs():
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, lr, ridge], meta_regressor=svr_rbf, random_state=42
    )

    # dense
    stack.fit(X1, y).predict(X1)
    mse = 0.21
    got = np.mean((stack.predict(X1) - y) ** 2)
    assert round(got, 2) == mse, got

    # sparse
    stack.fit(sparse.csr_matrix(X1), y)

    if Version(sklearn_version) < Version("0.21"):
        expected_value = 0.20
    elif Version(sklearn_version) < Version("0.22"):
        expected_value = 0.20
    else:
        expected_value = 0.21

    got = np.mean((stack.predict(sparse.csr_matrix(X1)) - y) ** 2)
    assert round(got, 2) == expected_value, got


def test_sparse_matrix_inputs_with_features_in_secondary():
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, lr, ridge],
        meta_regressor=svr_rbf,
        random_state=42,
        use_features_in_secondary=True,
    )

    # dense
    stack.fit(X1, y).predict(X1)
    mse = 0.20
    got = np.mean((stack.predict(X1) - y) ** 2)
    assert round(got, 2) == mse, got

    # sparse
    stack.fit(sparse.csr_matrix(X1), y)
    mse = 0.20
    got = np.mean((stack.predict(sparse.csr_matrix(X1)) - y) ** 2)
    assert round(got, 2) == mse, got


# Calling for np.random will break the existing tests by changing the
# seed for CV.
# As a temporary workaround, we use random package to generate random w.
random.seed(8)
w = np.array([random.random() for _ in range(40)])
# w  = np.random.random(40)


def test_sample_weight():
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, lr, ridge],
        meta_regressor=svr_rbf,
        cv=KFold(4, shuffle=True, random_state=7),
    )
    pred1 = stack.fit(X1, y, sample_weight=w).predict(X1)
    mse = 0.21  # 0.20770
    got = np.mean((stack.predict(X1) - y) ** 2)
    assert round(got, 2) == mse, "Expected %.2f, but got %.5f" % (mse, got)
    pred2 = stack.fit(X1, y).predict(X1)
    maxdiff = np.max(np.abs(pred1 - pred2))
    assert maxdiff > 1e-3, "max diff is %.4f" % maxdiff


def test_weight_ones():
    # sample_weight = None and sample_weight = ones
    # should give the same result, provided that the
    # randomness of the models is controled
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, lr, ridge],
        meta_regressor=svr_rbf,
        cv=KFold(5, shuffle=True, random_state=5),
    )
    pred1 = stack.fit(X1, y).predict(X1)
    pred2 = stack.fit(X1, y, sample_weight=np.ones(40)).predict(X1)
    assert np.max(np.abs(pred1 - pred2)) < 1e-3


def test_unsupported_regressor():
    # including regressor that does not support
    # sample_weight should raise error
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    knn = KNeighborsRegressor()
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    stack = StackingCVRegressor(
        regressors=[svr_lin, lr, ridge, knn], meta_regressor=svr_rbf
    )
    with pytest.raises(TypeError):
        stack.fit(X1, y, sample_weight=w).predict(X1)


def test_unsupported_meta_regressor():
    # meta regressor with no support for
    # sample_weight should raise error
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    knn = KNeighborsRegressor()
    stack = StackingCVRegressor(regressors=[svr_lin, lr, ridge], meta_regressor=knn)

    with pytest.raises(TypeError):
        stack.fit(X1, y, sample_weight=w).predict(X1)


def test_weight_unsupported_with_no_weight():
    # pass no weight to regressors with no weight support
    # should not be a problem
    lr = LinearRegression()
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    knn = KNeighborsRegressor()
    stack = StackingCVRegressor(regressors=[svr_lin, lr, knn], meta_regressor=ridge)
    stack.fit(X1, y).predict(X1)

    stack = StackingCVRegressor(regressors=[svr_lin, lr, ridge], meta_regressor=knn)
    stack.fit(X1, y).predict(X1)


def test_gridsearch_replace_mix():
    svr_lin = SVR(kernel="linear", gamma="auto")
    ridge = Ridge(random_state=1)
    svr_rbf = SVR(kernel="rbf", gamma="auto")
    lr = LinearRegression()
    lasso = Lasso(random_state=1)
    stack = StackingCVRegressor(
        regressors=[svr_lin, lasso, ridge], meta_regressor=svr_rbf, shuffle=False
    )

    params = {
        "regressors": [[svr_lin, lr]],
        "linearregression": [None, lasso, ridge],
        "svr__kernel": ["poly"],
    }

    if Version(sklearn_version) < Version("0.24.1"):
        grid = GridSearchCV(
            estimator=stack,
            param_grid=params,
            cv=KFold(5, shuffle=True, random_state=42),
            iid=False,
            refit=True,
            verbose=0,
        )
    else:
        grid = GridSearchCV(
            estimator=stack,
            param_grid=params,
            cv=KFold(5, shuffle=True, random_state=42),
            refit=True,
            verbose=0,
        )
    grid = grid.fit(X1, y)

    got1 = round(grid.best_score_, 2)
    got2 = len(grid.best_params_["regressors"])
    got3 = grid.best_params_["regressors"][0].kernel

    assert got1 == 0.73, got1
    assert got2 == 2, got2
    assert got3 == "poly", got3
