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2026-07-13 13:27:18 +08:00

1278 lines
50 KiB
Python

# coding: utf-8
import filecmp
import numbers
import re
import signal
import warnings
from copy import deepcopy
from pathlib import Path
import numpy as np
import pytest
from scipy import sparse
from sklearn.datasets import dump_svmlight_file, load_svmlight_file, make_blobs
from sklearn.model_selection import train_test_split
import lightgbm as lgb
from .utils import BuildInfo, dummy_obj, load_breast_cancer, mse_obj, np_assert_array_equal
def test_basic(tmp_path):
X_train, X_test, y_train, y_test = train_test_split(
*load_breast_cancer(return_X_y=True), test_size=0.1, random_state=2
)
feature_names = [f"Column_{i}" for i in range(X_train.shape[1])]
feature_names[1] = "a" * 1000 # set one name to a value longer than default buffer size
train_data = lgb.Dataset(X_train, label=y_train, feature_name=feature_names)
valid_data = train_data.create_valid(X_test, label=y_test)
params = {
"objective": "binary",
"metric": "auc",
"min_data": 10,
"num_leaves": 15,
"verbose": -1,
"num_threads": 1,
"max_bin": 255,
"gpu_use_dp": True,
}
bst = lgb.Booster(params, train_data)
bst.add_valid(valid_data, "valid_1")
for i in range(20):
bst.update()
if i % 10 == 0:
print(bst.eval_train(), bst.eval_valid())
assert train_data.get_feature_name() == feature_names
assert bst.current_iteration() == 20
assert bst.num_trees() == 20
assert bst.num_model_per_iteration() == 1
if not BuildInfo.has_cuda:
assert bst.lower_bound() == pytest.approx(-2.9040190126976606)
assert bst.upper_bound() == pytest.approx(3.3182142872462883)
tname = tmp_path / "svm_light.dat"
model_file = tmp_path / "model.txt"
bst.save_model(model_file)
pred_from_matr = bst.predict(X_test)
with open(tname, "w+b") as f:
dump_svmlight_file(X_test, y_test, f)
pred_from_file = bst.predict(tname)
np.testing.assert_allclose(pred_from_matr, pred_from_file)
# check saved model persistence
bst = lgb.Booster(params, model_file=model_file)
assert bst.feature_name() == feature_names
pred_from_model_file = bst.predict(X_test)
# we need to check the consistency of model file here, so test for exact equal
np_assert_array_equal(pred_from_matr, pred_from_model_file, strict=True)
# check early stopping is working. Make it stop very early, so the scores should be very close to zero
pred_parameter = {"pred_early_stop": True, "pred_early_stop_freq": 5, "pred_early_stop_margin": 1.5}
pred_early_stopping = bst.predict(X_test, **pred_parameter)
# scores likely to be different, but prediction should still be the same
np_assert_array_equal(np.sign(pred_from_matr), np.sign(pred_early_stopping), strict=True)
# test that shape is checked during prediction
bad_X_test = X_test[:, 1:]
bad_shape_error_msg = "The number of features in data*"
np.testing.assert_raises_regex(lgb.basic.LightGBMError, bad_shape_error_msg, bst.predict, bad_X_test)
np.testing.assert_raises_regex(
lgb.basic.LightGBMError, bad_shape_error_msg, bst.predict, sparse.csr_matrix(bad_X_test)
)
np.testing.assert_raises_regex(
lgb.basic.LightGBMError, bad_shape_error_msg, bst.predict, sparse.csc_matrix(bad_X_test)
)
with open(tname, "w+b") as f:
dump_svmlight_file(bad_X_test, y_test, f)
np.testing.assert_raises_regex(lgb.basic.LightGBMError, bad_shape_error_msg, bst.predict, tname)
with open(tname, "w+b") as f:
dump_svmlight_file(X_test, y_test, f, zero_based=False)
np.testing.assert_raises_regex(lgb.basic.LightGBMError, bad_shape_error_msg, bst.predict, tname)
def test_booster_rollback_one_iter(rng):
"""Test that Booster.rollback_one_iter() correctly rolls back one boosting iteration."""
X = rng.uniform(size=(100, 5))
y = rng.integers(0, 2, size=(100,))
X_test = rng.uniform(size=(10, 5))
train_data = lgb.Dataset(X, label=y)
params = {
"objective": "binary",
"verbose": -1,
}
bst = lgb.Booster(params, train_data)
# Train for 10 iterations
num_iterations = 10
for _ in range(num_iterations):
bst.update()
assert bst.current_iteration() == num_iterations
assert bst.num_trees() == num_iterations
# Get predictions before rollback
pred_before = bst.predict(X_test)
# Rollback one iteration
result = bst.rollback_one_iter()
# Verify rollback decremented both iteration count and tree count
assert bst.current_iteration() == num_iterations - 1
assert bst.num_trees() == num_iterations - 1
# Verify it returns self for method chaining
assert result is bst
# Verify predictions actually changed (proves tree was removed, not just counter)
pred_after = bst.predict(X_test)
assert not np.allclose(pred_before, pred_after)
# Verify multiple rollbacks work
bst.rollback_one_iter()
assert bst.current_iteration() == num_iterations - 2
assert bst.num_trees() == num_iterations - 2
class NumpySequence(lgb.Sequence):
def __init__(self, ndarray, batch_size):
self.ndarray = ndarray
self.batch_size = batch_size
def __getitem__(self, idx):
# The simple implementation is just a single "return self.ndarray[idx]"
# The following is for demo and testing purpose.
if isinstance(idx, numbers.Integral):
return self.ndarray[idx]
elif isinstance(idx, slice):
if not (idx.step is None or idx.step == 1):
raise NotImplementedError("No need to implement, caller will not set step by now")
return self.ndarray[idx.start : idx.stop]
elif isinstance(idx, list):
return self.ndarray[idx]
else:
raise TypeError(f"Sequence Index must be an integer/list/slice, got {type(idx).__name__}")
def __len__(self):
return len(self.ndarray)
def _create_sequence_from_ndarray(data, num_seq, batch_size):
if num_seq == 1:
return NumpySequence(data, batch_size)
nrow = data.shape[0]
seqs = []
seq_size = nrow // num_seq
for start in range(0, nrow, seq_size):
end = min(start + seq_size, nrow)
seq = NumpySequence(data[start:end], batch_size)
seqs.append(seq)
return seqs
@pytest.mark.parametrize("sample_count", [11, 100, None])
@pytest.mark.parametrize("batch_size", [3, None])
@pytest.mark.parametrize("include_0_and_nan", [False, True])
@pytest.mark.parametrize("num_seq", [1, 3])
def test_sequence(tmpdir, sample_count, batch_size, include_0_and_nan, num_seq, rng):
params = {"bin_construct_sample_cnt": sample_count}
nrow = 50
half_nrow = nrow // 2
ncol = 11
data = np.arange(nrow * ncol, dtype=np.float64).reshape((nrow, ncol))
if include_0_and_nan:
# whole col
data[:, 0] = 0
data[:, 1] = np.nan
# half col
data[:half_nrow, 3] = 0
data[:half_nrow, 2] = np.nan
data[half_nrow:-2, 4] = 0
data[:half_nrow, 4] = np.nan
X = data[:, :-1]
Y = data[:, -1]
npy_bin_fname = tmpdir / "data_from_npy.bin"
seq_bin_fname = tmpdir / "data_from_seq.bin"
# Create dataset from numpy array directly.
ds = lgb.Dataset(X, label=Y, params=params)
ds.save_binary(npy_bin_fname)
# Create dataset using Sequence.
seqs = _create_sequence_from_ndarray(X, num_seq, batch_size)
seq_ds = lgb.Dataset(seqs, label=Y, params=params)
seq_ds.save_binary(seq_bin_fname)
assert filecmp.cmp(npy_bin_fname, seq_bin_fname)
# Test for validation set.
# Select some random rows as valid data.
valid_idx = (rng.random(10) * nrow).astype(np.int32)
valid_data = data[valid_idx, :]
valid_X = valid_data[:, :-1]
valid_Y = valid_data[:, -1]
valid_npy_bin_fname = tmpdir / "valid_data_from_npy.bin"
valid_seq_bin_fname = tmpdir / "valid_data_from_seq.bin"
valid_seq2_bin_fname = tmpdir / "valid_data_from_seq2.bin"
valid_ds = lgb.Dataset(valid_X, label=valid_Y, params=params, reference=ds)
valid_ds.save_binary(valid_npy_bin_fname)
# From Dataset constructor, with dataset from numpy array.
valid_seqs = _create_sequence_from_ndarray(valid_X, num_seq, batch_size)
valid_seq_ds = lgb.Dataset(valid_seqs, label=valid_Y, params=params, reference=ds)
valid_seq_ds.save_binary(valid_seq_bin_fname)
assert filecmp.cmp(valid_npy_bin_fname, valid_seq_bin_fname)
# From Dataset.create_valid, with dataset from sequence.
valid_seq_ds2 = seq_ds.create_valid(valid_seqs, label=valid_Y, params=params)
valid_seq_ds2.save_binary(valid_seq2_bin_fname)
assert filecmp.cmp(valid_npy_bin_fname, valid_seq2_bin_fname)
@pytest.mark.parametrize("num_seq", [1, 2])
def test_sequence_get_data(num_seq, rng):
nrow = 20
ncol = 11
data = np.arange(nrow * ncol, dtype=np.float64).reshape((nrow, ncol))
X = data[:, :-1]
Y = data[:, -1]
seqs = _create_sequence_from_ndarray(data=X, num_seq=num_seq, batch_size=6)
seq_ds = lgb.Dataset(seqs, label=Y, params=None, free_raw_data=False).construct()
assert seq_ds.get_data() == seqs
used_indices = rng.choice(a=np.arange(nrow), size=nrow // 3, replace=False)
subset_data = seq_ds.subset(used_indices).construct()
np_assert_array_equal(subset_data.get_data(), X[sorted(used_indices)], strict=True)
def test_chunked_dataset():
X_train, X_test, y_train, y_test = train_test_split(
*load_breast_cancer(return_X_y=True), test_size=0.1, random_state=2
)
chunk_size = X_train.shape[0] // 10 + 1
X_train = [X_train[i * chunk_size : (i + 1) * chunk_size, :] for i in range(X_train.shape[0] // chunk_size + 1)]
X_test = [X_test[i * chunk_size : (i + 1) * chunk_size, :] for i in range(X_test.shape[0] // chunk_size + 1)]
train_data = lgb.Dataset(X_train, label=y_train, params={"bin_construct_sample_cnt": 100})
valid_data = train_data.create_valid(X_test, label=y_test, params={"bin_construct_sample_cnt": 100})
train_data.construct()
valid_data.construct()
def test_chunked_dataset_linear():
X_train, X_test, y_train, y_test = train_test_split(
*load_breast_cancer(return_X_y=True), test_size=0.1, random_state=2
)
chunk_size = X_train.shape[0] // 10 + 1
X_train = [X_train[i * chunk_size : (i + 1) * chunk_size, :] for i in range(X_train.shape[0] // chunk_size + 1)]
X_test = [X_test[i * chunk_size : (i + 1) * chunk_size, :] for i in range(X_test.shape[0] // chunk_size + 1)]
params = {"bin_construct_sample_cnt": 100, "linear_tree": True}
train_data = lgb.Dataset(X_train, label=y_train, params=params)
valid_data = train_data.create_valid(X_test, label=y_test, params=params)
train_data.construct()
valid_data.construct()
def test_save_dataset_subset_and_load_from_file(tmp_path, rng):
data = rng.standard_normal(size=(100, 2))
params = {"max_bin": 50, "min_data_in_bin": 10}
ds = lgb.Dataset(data, params=params)
ds.subset([1, 2, 3, 5, 8]).save_binary(tmp_path / "subset.bin")
lgb.Dataset(tmp_path / "subset.bin", params=params).construct()
def test_save_binary_raises_on_truncated_write(tmp_path, rng):
resource = pytest.importorskip("resource")
if not hasattr(signal, "SIGXFSZ"):
pytest.skip("SIGXFSZ is not available on this platform")
data = rng.standard_normal(size=(1000, 20))
ds = lgb.Dataset(data).construct()
original_limit = resource.getrlimit(resource.RLIMIT_FSIZE)
original_signal_handler = signal.getsignal(signal.SIGXFSZ)
try:
signal.signal(signal.SIGXFSZ, signal.SIG_IGN)
resource.setrlimit(resource.RLIMIT_FSIZE, (4096, original_limit[1]))
with pytest.raises(lgb.basic.LightGBMError, match="Cannot write binary data"):
ds.save_binary(tmp_path / "truncated.bin")
finally:
resource.setrlimit(resource.RLIMIT_FSIZE, original_limit)
signal.signal(signal.SIGXFSZ, original_signal_handler)
def test_subset_group():
rank_example_dir = Path(__file__).absolute().parents[2] / "examples" / "lambdarank"
X_train, y_train = load_svmlight_file(str(rank_example_dir / "rank.train"))
q_train = np.loadtxt(str(rank_example_dir / "rank.train.query"))
lgb_train = lgb.Dataset(X_train, y_train, group=q_train)
assert len(lgb_train.get_group()) == 201
subset = lgb_train.subset(list(range(10))).construct()
subset_group = subset.get_group()
assert len(subset_group) == 2
assert subset_group[0] == 1
assert subset_group[1] == 9
def test_add_features_throws_if_num_data_unequal(rng):
X1 = rng.uniform(size=(100, 1))
X2 = rng.uniform(size=(10, 1))
d1 = lgb.Dataset(X1).construct()
d2 = lgb.Dataset(X2).construct()
with pytest.raises(
lgb.basic.LightGBMError, match="Cannot add features from other Dataset with a different number of rows"
):
d1.add_features_from(d2)
def test_add_features_throws_if_datasets_unconstructed(rng):
X1 = rng.uniform(size=(100, 1))
X2 = rng.uniform(size=(100, 1))
err_msg = "Both source and target Datasets must be constructed before adding features"
d1 = lgb.Dataset(X1)
d2 = lgb.Dataset(X2)
with pytest.raises(ValueError, match=err_msg):
d1.add_features_from(d2)
d1 = lgb.Dataset(X1).construct()
d2 = lgb.Dataset(X2)
with pytest.raises(ValueError, match=err_msg):
d1.add_features_from(d2)
d1 = lgb.Dataset(X1)
d2 = lgb.Dataset(X2).construct()
with pytest.raises(ValueError, match=err_msg):
d1.add_features_from(d2)
def test_add_features_equal_data_on_alternating_used_unused(tmp_path, rng):
X = rng.uniform(size=(100, 5))
X[:, [1, 3]] = 0
names = [f"col_{i}" for i in range(5)]
for j in range(1, 5):
d1 = lgb.Dataset(X[:, :j], feature_name=names[:j]).construct()
d2 = lgb.Dataset(X[:, j:], feature_name=names[j:]).construct()
d1.add_features_from(d2)
d1name = tmp_path / "d1.txt"
d1._dump_text(d1name)
d = lgb.Dataset(X, feature_name=names).construct()
dname = tmp_path / "d.txt"
d._dump_text(dname)
with open(d1name, "rt") as d1f:
d1txt = d1f.read()
with open(dname, "rt") as df:
dtxt = df.read()
assert dtxt == d1txt
def test_add_features_same_booster_behaviour(tmp_path, rng):
X = rng.uniform(size=(100, 5))
X[:, [1, 3]] = 0
names = [f"col_{i}" for i in range(5)]
for j in range(1, 5):
d1 = lgb.Dataset(X[:, :j], feature_name=names[:j]).construct()
d2 = lgb.Dataset(X[:, j:], feature_name=names[j:]).construct()
d1.add_features_from(d2)
d = lgb.Dataset(X, feature_name=names).construct()
y = rng.uniform(size=(100,))
d1.set_label(y)
d.set_label(y)
b1 = lgb.Booster(train_set=d1)
b = lgb.Booster(train_set=d)
for _ in range(10):
b.update()
b1.update()
dname = tmp_path / "d.txt"
d1name = tmp_path / "d1.txt"
b1.save_model(d1name)
b.save_model(dname)
with open(dname, "rt") as df:
dtxt = df.read()
with open(d1name, "rt") as d1f:
d1txt = d1f.read()
assert dtxt == d1txt
def test_add_features_from_different_sources(rng):
pd = pytest.importorskip("pandas")
n_row = 100
n_col = 5
X = rng.uniform(size=(n_row, n_col))
xxs = [X, sparse.csr_matrix(X), pd.DataFrame(X)]
names = [f"col_{i}" for i in range(n_col)]
seq = _create_sequence_from_ndarray(X, 1, 30)
seq_ds = lgb.Dataset(seq, feature_name=names, free_raw_data=False).construct()
npy_list_ds = lgb.Dataset(
[X[: n_row // 2, :], X[n_row // 2 :, :]], feature_name=names, free_raw_data=False
).construct()
immergeable_dds = [seq_ds, npy_list_ds]
for x_1 in xxs:
# test that method works even with free_raw_data=True
d1 = lgb.Dataset(x_1, feature_name=names, free_raw_data=True).construct()
d2 = lgb.Dataset(x_1, feature_name=names, free_raw_data=True).construct()
d1.add_features_from(d2)
assert d1.data is None
# test that method works but sets raw data to None in case of immergeable data types
d1 = lgb.Dataset(x_1, feature_name=names, free_raw_data=False).construct()
for d2 in immergeable_dds:
d1.add_features_from(d2)
assert d1.data is None
# test that method works for different data types
d1 = lgb.Dataset(x_1, feature_name=names, free_raw_data=False).construct()
res_feature_names = deepcopy(names)
for idx, x_2 in enumerate(xxs, 2):
original_type = type(d1.get_data())
d2 = lgb.Dataset(x_2, feature_name=names, free_raw_data=False).construct()
d1.add_features_from(d2)
assert isinstance(d1.get_data(), original_type)
assert d1.get_data().shape == (n_row, n_col * idx)
res_feature_names += [f"D{idx}_{name}" for name in names]
assert d1.feature_name == res_feature_names
def test_add_features_does_not_fail_if_initial_dataset_has_zero_informative_features(capsys, rng):
arr_a = np.zeros((100, 1), dtype=np.float32)
arr_b = rng.uniform(size=(100, 5))
dataset_a = lgb.Dataset(arr_a, params={"verbose": 0}).construct()
expected_msg = (
"[LightGBM] [Warning] There are no meaningful features which satisfy "
"the provided configuration. Decreasing Dataset parameters min_data_in_bin "
"or min_data_in_leaf and re-constructing Dataset might resolve this warning.\n"
)
log_lines = capsys.readouterr().out
assert expected_msg in log_lines
dataset_b = lgb.Dataset(arr_b).construct()
original_handle = dataset_a._handle.value
dataset_a.add_features_from(dataset_b)
assert dataset_a.num_feature() == 6
assert dataset_a.num_data() == 100
assert dataset_a._handle.value == original_handle
def test_cegb_affects_behavior(tmp_path, rng):
X = rng.uniform(size=(100, 5))
X[:, [1, 3]] = 0
y = rng.uniform(size=(100,))
names = [f"col_{i}" for i in range(5)]
ds = lgb.Dataset(X, feature_name=names).construct()
ds.set_label(y)
base = lgb.Booster(train_set=ds)
for _ in range(10):
base.update()
basename = tmp_path / "basename.txt"
base.save_model(basename)
with open(basename, "rt") as f:
basetxt = f.read()
# Set extremely harsh penalties, so CEGB will block most splits.
cases = [
{"cegb_penalty_feature_coupled": [50, 100, 10, 25, 30]},
{"cegb_penalty_feature_lazy": [1, 2, 3, 4, 5]},
{"cegb_penalty_split": 1},
]
for case in cases:
booster = lgb.Booster(train_set=ds, params=case)
for _ in range(10):
booster.update()
casename = tmp_path / "casename.txt"
booster.save_model(casename)
with open(casename, "rt") as f:
casetxt = f.read()
assert basetxt != casetxt
def test_cegb_scaling_equalities(tmp_path, rng):
X = rng.uniform(size=(100, 5))
X[:, [1, 3]] = 0
y = rng.uniform(size=(100,))
names = [f"col_{i}" for i in range(5)]
ds = lgb.Dataset(X, feature_name=names).construct()
ds.set_label(y)
# Compare pairs of penalties, to ensure scaling works as intended
pairs = [
(
{"cegb_penalty_feature_coupled": [1, 2, 1, 2, 1]},
{"cegb_penalty_feature_coupled": [0.5, 1, 0.5, 1, 0.5], "cegb_tradeoff": 2},
),
(
{"cegb_penalty_feature_lazy": [0.01, 0.02, 0.03, 0.04, 0.05]},
{"cegb_penalty_feature_lazy": [0.005, 0.01, 0.015, 0.02, 0.025], "cegb_tradeoff": 2},
),
({"cegb_penalty_split": 1}, {"cegb_penalty_split": 2, "cegb_tradeoff": 0.5}),
]
for p1, p2 in pairs:
booster1 = lgb.Booster(train_set=ds, params=p1)
booster2 = lgb.Booster(train_set=ds, params=p2)
for _ in range(10):
booster1.update()
booster2.update()
p1name = tmp_path / "p1.txt"
# Reset booster1's parameters to p2, so the parameter section of the file matches.
booster1.reset_parameter(p2)
booster1.save_model(p1name)
with open(p1name, "rt") as f:
p1txt = f.read()
p2name = tmp_path / "p2.txt"
booster2.save_model(p2name)
with open(p2name, "rt") as f:
p2txt = f.read()
assert p1txt == p2txt
def test_consistent_state_for_dataset_fields():
def check_asserts(data):
np.testing.assert_allclose(data.label, data.get_label())
np.testing.assert_allclose(data.label, data.get_field("label"))
assert not np.isnan(data.label[0])
assert not np.isinf(data.label[1])
np.testing.assert_allclose(data.weight, data.get_weight())
np.testing.assert_allclose(data.weight, data.get_field("weight"))
assert not np.isnan(data.weight[0])
assert not np.isinf(data.weight[1])
np.testing.assert_allclose(data.init_score, data.get_init_score())
np.testing.assert_allclose(data.init_score, data.get_field("init_score"))
assert not np.isnan(data.init_score[0])
assert not np.isinf(data.init_score[1])
assert np.all(np.isclose([data.label[0], data.weight[0], data.init_score[0]], data.label[0]))
assert data.label[1] == pytest.approx(data.weight[1])
assert data.feature_name == data.get_feature_name()
X, y = load_breast_cancer(return_X_y=True)
sequence = np.ones(y.shape[0])
sequence[0] = np.nan
sequence[1] = np.inf
feature_names = [f"f{i}" for i in range(X.shape[1])]
lgb_data = lgb.Dataset(X, sequence, weight=sequence, init_score=sequence, feature_name=feature_names).construct()
check_asserts(lgb_data)
lgb_data = lgb.Dataset(X, y).construct()
lgb_data.set_label(sequence)
lgb_data.set_weight(sequence)
lgb_data.set_init_score(sequence)
lgb_data.set_feature_name(feature_names)
check_asserts(lgb_data)
def test_dataset_construction_overwrites_user_provided_metadata_fields():
X = np.array([[1.0, 2.0], [3.0, 4.0]])
position = np.array([0.0, 1.0], dtype=np.float32)
if BuildInfo.has_cuda:
position = None
dtrain = lgb.Dataset(
X,
params={"min_data_in_bin": 1, "min_data_in_leaf": 1, "verbosity": -1},
group=[1, 1],
init_score=[0.312, 0.708],
label=[1, 2],
position=position,
weight=[0.5, 1.5],
)
# unconstructed, get_* methods should return whatever was provided
assert dtrain.group == [1, 1]
assert dtrain.get_group() == [1, 1]
assert dtrain.init_score == [0.312, 0.708]
assert dtrain.get_init_score() == [0.312, 0.708]
assert dtrain.label == [1, 2]
assert dtrain.get_label() == [1, 2]
if not BuildInfo.has_cuda:
np_assert_array_equal(dtrain.position, np.array([0.0, 1.0], dtype=np.float32), strict=True)
np_assert_array_equal(dtrain.get_position(), np.array([0.0, 1.0], dtype=np.float32), strict=True)
assert dtrain.weight == [0.5, 1.5]
assert dtrain.get_weight() == [0.5, 1.5]
# before construction, get_field() should raise an exception
for field_name in ["group", "init_score", "label", "position", "weight"]:
with pytest.raises(Exception, match=f"Cannot get {field_name} before construct Dataset"):
dtrain.get_field(field_name)
# constructed, get_* methods should return numpy arrays, even when the provided
# input was a list of floats or ints
dtrain.construct()
expected_group = np.array([1, 1], dtype=np.int32)
np_assert_array_equal(dtrain.group, expected_group, strict=True)
np_assert_array_equal(dtrain.get_group(), expected_group, strict=True)
# get_field("group") returns a numpy array with boundaries, instead of size
np_assert_array_equal(dtrain.get_field("group"), np.array([0, 1, 2], dtype=np.int32), strict=True)
expected_init_score = np.array(
[0.312, 0.708],
)
np_assert_array_equal(dtrain.init_score, expected_init_score, strict=True)
np_assert_array_equal(dtrain.get_init_score(), expected_init_score, strict=True)
np_assert_array_equal(dtrain.get_field("init_score"), expected_init_score, strict=True)
expected_label = np.array([1, 2], dtype=np.float32)
np_assert_array_equal(dtrain.label, expected_label, strict=True)
np_assert_array_equal(dtrain.get_label(), expected_label, strict=True)
np_assert_array_equal(dtrain.get_field("label"), expected_label, strict=True)
if not BuildInfo.has_cuda:
# NOTE: "position" is converted to int32 on the C++ side and remapped to dense
# internal indices in encounter order. Here the input [0, 1] is already dense
# starting from 0 in encounter order, so the remap is the identity.
expected_position = np.array([0, 1], dtype=np.int32)
np_assert_array_equal(dtrain.position, expected_position, strict=True)
np_assert_array_equal(dtrain.get_position(), expected_position, strict=True)
np_assert_array_equal(dtrain.get_field("position"), expected_position, strict=True)
expected_weight = np.array([0.5, 1.5], dtype=np.float32)
np_assert_array_equal(dtrain.weight, expected_weight, strict=True)
np_assert_array_equal(dtrain.get_weight(), expected_weight, strict=True)
np_assert_array_equal(dtrain.get_field("weight"), expected_weight, strict=True)
@pytest.mark.skipif(
BuildInfo.has_cuda,
reason="Positions in learning to rank is not supported in CUDA version yet",
)
def test_set_position_updates_self_position_with_remapped_int32_values():
# Position values are remapped to dense int32 indices in the order they are first
# encountered. With input [3, 1, 0, 2, 4, 3, 1, 0, 2, 4]:
# 3 -> 0 (first encountered), 1 -> 1, 0 -> 2, 2 -> 3, 4 -> 4
X = np.arange(20, dtype=np.float64).reshape(10, 2)
y = np.arange(10, dtype=np.float64)
position = np.array([3, 1, 0, 2, 4, 3, 1, 0, 2, 4], dtype=np.int64)
expected = np.array([0, 1, 2, 3, 4, 0, 1, 2, 3, 4], dtype=np.int32)
# set via constructor
dtrain = lgb.Dataset(
X,
label=y,
position=position,
params={"min_data_in_bin": 1, "min_data_in_leaf": 1, "verbosity": -1},
).construct()
np_assert_array_equal(dtrain.position, expected, strict=True)
np_assert_array_equal(dtrain.get_position(), expected, strict=True)
np_assert_array_equal(dtrain.get_field("position"), expected, strict=True)
# set via set_position() on an already-constructed Dataset
dtrain2 = lgb.Dataset(
X,
label=y,
params={"min_data_in_bin": 1, "min_data_in_leaf": 1, "verbosity": -1},
).construct()
dtrain2.set_position(position)
np_assert_array_equal(dtrain2.position, expected, strict=True)
np_assert_array_equal(dtrain2.get_position(), expected, strict=True)
np_assert_array_equal(dtrain2.get_field("position"), expected, strict=True)
def test_dataset_construction_with_high_cardinality_categorical_succeeds(rng):
pd = pytest.importorskip("pandas")
X = pd.DataFrame({"x1": rng.integers(low=0, high=5_000, size=(10_000,))})
y = rng.uniform(size=(10_000,))
ds = lgb.Dataset(X, y, categorical_feature=["x1"])
ds.construct()
assert ds.num_data() == 10_000
assert ds.num_feature() == 1
def test_choose_param_value():
original_params = {
"local_listen_port": 1234,
"port": 2222,
"metric": "auc",
"num_trees": 81,
"n_iter": 13,
}
# should resolve duplicate aliases, and prefer the main parameter
params = lgb.basic._choose_param_value(
main_param_name="local_listen_port", params=original_params, default_value=5555
)
assert params["local_listen_port"] == 1234
assert "port" not in params
# should choose the highest priority alias and set that value on main param
# if only aliases are used
params = lgb.basic._choose_param_value(main_param_name="num_iterations", params=params, default_value=17)
assert params["num_iterations"] == 13
assert "num_trees" not in params
assert "n_iter" not in params
# should use the default if main param and aliases are missing
params = lgb.basic._choose_param_value(main_param_name="learning_rate", params=params, default_value=0.789)
assert params["learning_rate"] == 0.789
# all changes should be made on copies and not modify the original
expected_params = {
"local_listen_port": 1234,
"port": 2222,
"metric": "auc",
"num_trees": 81,
"n_iter": 13,
}
assert original_params == expected_params
def test_choose_param_value_preserves_nones():
# preserves None found for main param and still removes aliases
params = lgb.basic._choose_param_value(
main_param_name="num_threads",
params={"num_threads": None, "n_jobs": 4, "objective": "regression"},
default_value=2,
)
assert params == {"num_threads": None, "objective": "regression"}
# correctly chooses value when only an alias is provided
params = lgb.basic._choose_param_value(
main_param_name="num_threads", params={"n_jobs": None, "objective": "regression"}, default_value=2
)
assert params == {"num_threads": None, "objective": "regression"}
# adds None if that's given as the default and param not found
params = lgb.basic._choose_param_value(
main_param_name="min_data_in_leaf", params={"objective": "regression"}, default_value=None
)
assert params == {"objective": "regression", "min_data_in_leaf": None}
@pytest.mark.parametrize("objective_alias", lgb.basic._ConfigAliases.get("objective"))
def test_choose_param_value_objective(objective_alias):
# If callable is found in objective
params = {objective_alias: dummy_obj}
params = lgb.basic._choose_param_value(main_param_name="objective", params=params, default_value=None)
assert params["objective"] == dummy_obj
# Value in params should be preferred to the default_value passed from keyword arguments
params = {objective_alias: dummy_obj}
params = lgb.basic._choose_param_value(main_param_name="objective", params=params, default_value=mse_obj)
assert params["objective"] == dummy_obj
# None of objective or its aliases in params, but default_value is callable.
params = {}
params = lgb.basic._choose_param_value(main_param_name="objective", params=params, default_value=mse_obj)
assert params["objective"] == mse_obj
@pytest.mark.parametrize("collection", ["1d_np", "2d_np", "pd_float", "pd_str", "1d_list", "2d_list"])
@pytest.mark.parametrize("dtype", [np.float32, np.float64])
def test_list_to_1d_numpy(collection, dtype, rng):
collection2y = {
"1d_np": rng.uniform(size=(10,)),
"2d_np": rng.uniform(size=(10, 1)),
"pd_float": rng.uniform(size=(10,)),
"pd_str": ["a", "b"],
"1d_list": [1] * 10,
"2d_list": [[1], [2]],
}
y = collection2y[collection]
custom_name = "my_custom_variable"
if collection.startswith("pd"):
pd = pytest.importorskip("pandas")
y = pd.Series(y)
if pd.api.types.is_object_dtype(y):
with pytest.raises(
ValueError,
match=r"pandas dtypes must be int, float or bool\.\nFields with bad pandas dtypes: 0: object",
):
lgb.basic._list_to_1d_numpy(data=y, dtype=np.float32, name=custom_name)
return
elif pd.api.types.is_string_dtype(y):
with pytest.raises(
ValueError, match=r"pandas dtypes must be int, float or bool\.\nFields with bad pandas dtypes: 0: str"
):
lgb.basic._list_to_1d_numpy(data=y, dtype=np.float32, name=custom_name)
return
if isinstance(y, np.ndarray) and len(y.shape) == 2:
with pytest.warns(UserWarning, match="column-vector"):
lgb.basic._list_to_1d_numpy(data=y, dtype=np.float32, name=custom_name)
return
elif isinstance(y, list) and isinstance(y[0], list):
err_msg = (
rf"Wrong type\(list\) for {custom_name}.\n"
r"It should be list, numpy 1-D array or pandas Series"
)
with pytest.raises(TypeError, match=err_msg):
lgb.basic._list_to_1d_numpy(data=y, dtype=np.float32, name=custom_name)
return
result = lgb.basic._list_to_1d_numpy(data=y, dtype=dtype, name=custom_name)
assert result.size == 10
assert result.dtype == dtype
@pytest.mark.parametrize("init_score_type", ["array", "dataframe", "list"])
def test_init_score_for_multiclass_classification(init_score_type, rng):
init_score = [[i * 10 + j for j in range(3)] for i in range(10)]
if init_score_type == "array":
init_score = np.array(init_score)
elif init_score_type == "dataframe":
pd = pytest.importorskip("pandas")
init_score = pd.DataFrame(init_score)
data = rng.uniform(size=(10, 2))
ds = lgb.Dataset(data, init_score=init_score).construct()
np.testing.assert_equal(ds.get_field("init_score"), init_score)
np.testing.assert_equal(ds.init_score, init_score)
def test_smoke_custom_parser(tmp_path):
data_path = Path(__file__).absolute().parents[2] / "examples" / "binary_classification" / "binary.train"
parser_config_file = tmp_path / "parser.ini"
with open(parser_config_file, "w") as fout:
fout.write('{"className": "dummy", "id": "1"}')
data = lgb.Dataset(data_path, params={"parser_config_file": parser_config_file})
with pytest.raises(
lgb.basic.LightGBMError, match="Cannot find parser class 'dummy', please register first or check config format"
):
data.construct()
def test_param_aliases():
aliases = lgb.basic._ConfigAliases.aliases
assert isinstance(aliases, dict)
assert len(aliases) > 100
assert all(isinstance(i, list) for i in aliases.values())
assert all(len(i) >= 1 for i in aliases.values())
assert all(k in v for k, v in aliases.items())
assert lgb.basic._ConfigAliases.get("config", "task") == {"config", "config_file", "task", "task_type"}
assert lgb.basic._ConfigAliases.get_sorted("min_data_in_leaf") == [
"min_data_in_leaf",
"min_data",
"min_samples_leaf",
"min_child_samples",
"min_data_per_leaf",
]
def _bad_gradients(preds, _):
rng = np.random.default_rng()
# "bad" = 1 element too many
size = (len(preds) + 1,)
return rng.standard_normal(size=size), rng.uniform(size=size)
def _good_gradients(preds, _):
rng = np.random.default_rng()
return rng.standard_normal(size=preds.shape), rng.uniform(size=preds.shape)
def test_custom_objective_safety(rng):
nrows = 100
X = rng.standard_normal(size=(nrows, 5))
y_binary = np.arange(nrows) % 2
classes = [0, 1, 2]
nclass = len(classes)
y_multiclass = np.arange(nrows) % nclass
ds_binary = lgb.Dataset(X, y_binary).construct()
ds_multiclass = lgb.Dataset(X, y_multiclass).construct()
bad_bst_binary = lgb.Booster({"objective": "none"}, ds_binary)
good_bst_binary = lgb.Booster({"objective": "none"}, ds_binary)
bad_bst_multi = lgb.Booster({"objective": "none", "num_class": nclass}, ds_multiclass)
good_bst_multi = lgb.Booster({"objective": "none", "num_class": nclass}, ds_multiclass)
good_bst_binary.update(fobj=_good_gradients)
with pytest.raises(ValueError, match=re.escape("number of models per one iteration (1)")):
bad_bst_binary.update(fobj=_bad_gradients)
good_bst_multi.update(fobj=_good_gradients)
with pytest.raises(ValueError, match=re.escape(f"number of models per one iteration ({nclass})")):
bad_bst_multi.update(fobj=_bad_gradients)
@pytest.mark.parametrize("dtype", [np.float32, np.float64])
@pytest.mark.parametrize("feature_name", [["x1", "x2"], "auto"])
def test_no_copy_when_single_float_dtype_dataframe(dtype, feature_name, rng):
pd = pytest.importorskip("pandas")
X = rng.uniform(size=(10, 2)).astype(dtype)
# copy=False is necessary because starting with pandas 3.0, pd.DataFrame() creates
# a copy of the input numpy array by default
# ref: https://github.com/pandas-dev/pandas/issues/58913
df = pd.DataFrame(X, copy=False)
built_data = lgb.basic._data_from_pandas(
data=df, feature_name=feature_name, categorical_feature="auto", pandas_categorical=None
)[0]
assert built_data.dtype == dtype
assert np.shares_memory(X, built_data)
@pytest.mark.parametrize("feature_name", [["x1"], [42], "auto"])
@pytest.mark.parametrize("categories", ["seen", "unseen"])
def test_categorical_code_conversion_doesnt_modify_original_data(feature_name, categories, rng):
pd = pytest.importorskip("pandas")
X = rng.choice(a=["a", "b"], size=(100, 1))
column_name = "a" if feature_name == "auto" else feature_name[0]
df = pd.DataFrame(X.copy(), columns=[column_name], dtype="category")
if categories == "seen":
pandas_categorical = [["a", "b"]]
else:
pandas_categorical = [["a"]]
data = lgb.basic._data_from_pandas(
data=df,
feature_name=feature_name,
categorical_feature="auto",
pandas_categorical=pandas_categorical,
)[0]
# check that the original data wasn't modified
np.testing.assert_equal(df[column_name], X[:, 0])
# check that the built data has the codes
if categories == "seen":
# if all categories were seen during training we just take the codes
codes = df[column_name].cat.codes
else:
# if we only saw 'a' during training we just replace its code
# and leave the rest as nan
a_code = df[column_name].cat.categories.get_loc("a")
codes = np.where(df[column_name] == "a", a_code, np.nan)
np.testing.assert_equal(codes, data[:, 0])
@pytest.mark.parametrize("min_data_in_bin", [2, 10])
def test_feature_num_bin(min_data_in_bin, rng):
X = np.vstack(
[
rng.uniform(size=(100,)),
np.array([1, 2] * 50),
np.array([0, 1, 2] * 33 + [0]),
np.array([1, 2] * 49 + 2 * [np.nan]),
np.zeros(100),
rng.choice(a=[0, 1], size=(100,)),
]
).T
n_continuous = X.shape[1] - 1
feature_name = [f"x{i}" for i in range(n_continuous)] + ["cat1"]
ds_kwargs = {
"params": {"min_data_in_bin": min_data_in_bin},
"categorical_feature": [n_continuous], # last feature
}
ds = lgb.Dataset(X, feature_name=feature_name, **ds_kwargs).construct()
expected_num_bins = [
100 // min_data_in_bin + 1, # extra bin for zero
3, # 0, 1, 2
3, # 0, 1, 2
4, # 0, 1, 2 + nan
0, # unused
3, # 0, 1 + nan
]
actual_num_bins = [ds.feature_num_bin(i) for i in range(X.shape[1])]
assert actual_num_bins == expected_num_bins
# test using defined feature names
bins_by_name = [ds.feature_num_bin(name) for name in feature_name]
assert bins_by_name == expected_num_bins
# test using default feature names
ds_no_names = lgb.Dataset(X, **ds_kwargs).construct()
default_names = [f"Column_{i}" for i in range(X.shape[1])]
bins_by_default_name = [ds_no_names.feature_num_bin(name) for name in default_names]
assert bins_by_default_name == expected_num_bins
# check for feature indices outside of range
num_features = X.shape[1]
with pytest.raises(
lgb.basic.LightGBMError,
match=(
f"Tried to retrieve number of bins for feature index {num_features}, "
f"but the valid feature indices are \\[0, {num_features - 1}\\]."
),
):
ds.feature_num_bin(num_features)
def test_feature_num_bin_with_max_bin_by_feature(rng):
X = rng.uniform(size=(100, 3))
max_bin_by_feature = rng.integers(low=3, high=30, size=X.shape[1])
ds = lgb.Dataset(X, params={"max_bin_by_feature": max_bin_by_feature}).construct()
actual_num_bins = [ds.feature_num_bin(i) for i in range(X.shape[1])]
np.testing.assert_equal(actual_num_bins, max_bin_by_feature)
def test_set_leaf_output():
X, y = load_breast_cancer(return_X_y=True)
ds = lgb.Dataset(X, y)
bst = lgb.Booster({"num_leaves": 2}, ds)
bst.update()
y_pred = bst.predict(X)
for leaf_id in range(2):
leaf_output = bst.get_leaf_output(tree_id=0, leaf_id=leaf_id)
bst.set_leaf_output(tree_id=0, leaf_id=leaf_id, value=leaf_output + 1)
np.testing.assert_allclose(bst.predict(X), y_pred + 1)
def test_feature_names_are_set_correctly_when_no_feature_names_passed_into_Dataset(rng):
ds = lgb.Dataset(
data=rng.standard_normal(size=(100, 3)),
)
assert ds.construct().feature_name == ["Column_0", "Column_1", "Column_2"]
def test_set_feature_name_updates_has_non_default_feature_names(rng):
ds = lgb.Dataset(data=rng.standard_normal(size=(100, 3)), label=rng.integers(0, 2, size=100))
assert ds._has_non_default_feature_names is False
ds.construct()
assert ds._has_non_default_feature_names is False
assert ds.get_feature_name() == ["Column_0", "Column_1", "Column_2"]
ds.set_feature_name(["a", "b", "c"])
assert ds._has_non_default_feature_names is True
assert ds.get_feature_name() == ["a", "b", "c"]
# NOTE: this intentionally contains values where num_leaves <, ==, and > (max_depth^2)
@pytest.mark.parametrize(("max_depth", "num_leaves"), [(-1, 3), (-1, 50), (5, 3), (5, 31), (5, 32), (8, 3), (8, 31)])
def test_max_depth_warning_is_not_raised_if_num_leaves_is_also_provided(capsys, num_leaves, max_depth):
X, y = make_blobs(n_samples=1_000, n_features=1, centers=2)
lgb.Booster(
params={
"objective": "binary",
"max_depth": max_depth,
"num_leaves": num_leaves,
"num_iterations": 1,
"verbose": 0,
},
train_set=lgb.Dataset(X, label=y),
)
assert "Provided parameters constrain tree depth" not in capsys.readouterr().out
# NOTE: max_depth < 5 is significant here because the default for num_leaves=31. With max_depth=5,
# a full depth-wise tree would have 2^5 = 32 leaves.
@pytest.mark.parametrize("max_depth", [1, 2, 3, 4])
def test_max_depth_warning_is_not_raised_if_max_depth_gt_1_and_lt_5_and_num_leaves_omitted(capsys, max_depth):
X, y = make_blobs(n_samples=1_000, n_features=1, centers=2)
lgb.Booster(
params={
"objective": "binary",
"max_depth": max_depth,
"num_iterations": 1,
"verbose": 0,
},
train_set=lgb.Dataset(X, label=y),
)
assert "Provided parameters constrain tree depth" not in capsys.readouterr().out
@pytest.mark.parametrize("max_depth", [5, 6, 7, 8, 9])
def test_max_depth_warning_is_raised_if_max_depth_gte_5_and_num_leaves_omitted(capsys, max_depth):
X, y = make_blobs(n_samples=1_000, n_features=1, centers=2)
lgb.Booster(
params={
"objective": "binary",
"max_depth": max_depth,
"num_iterations": 1,
"verbose": 0,
},
train_set=lgb.Dataset(X, label=y),
)
expected_warning = (
f"[LightGBM] [Warning] Provided parameters constrain tree depth (max_depth={max_depth}) without explicitly "
f"setting 'num_leaves'. This can lead to underfitting. To resolve this warning, pass 'num_leaves' (<={2**max_depth}) "
"in params. Alternatively, pass (max_depth=-1) and just use 'num_leaves' to constrain model complexity."
)
assert expected_warning in capsys.readouterr().out
@pytest.mark.parametrize("order", ["C", "F"])
@pytest.mark.parametrize("dtype", ["float32", "int64"])
def test_no_copy_in_dataset_from_numpy_2d(rng, order, dtype):
X = rng.random(size=(100, 3))
X = np.require(X, dtype=dtype, requirements=order)
X1d, layout = lgb.basic._np2d_to_np1d(X)
if order == "F":
assert layout == lgb.basic._C_API_IS_COL_MAJOR
else:
assert layout == lgb.basic._C_API_IS_ROW_MAJOR
if dtype == "float32":
assert np.shares_memory(X, X1d)
else:
# makes a copy
assert not np.shares_memory(X, X1d)
def test_equal_datasets_from_row_major_and_col_major_data(tmp_path):
# row-major dataset
X_row, y = make_blobs(n_samples=1_000, n_features=3, centers=2)
assert X_row.flags["C_CONTIGUOUS"]
assert not X_row.flags["F_CONTIGUOUS"]
ds_row = lgb.Dataset(X_row, y)
ds_row_path = tmp_path / "ds_row.txt"
ds_row._dump_text(ds_row_path)
# col-major dataset
X_col = np.asfortranarray(X_row)
assert X_col.flags["F_CONTIGUOUS"]
assert not X_col.flags["C_CONTIGUOUS"]
ds_col = lgb.Dataset(X_col, y)
ds_col_path = tmp_path / "ds_col.txt"
ds_col._dump_text(ds_col_path)
# check datasets are equal
assert filecmp.cmp(ds_row_path, ds_col_path)
def test_equal_datasets_from_one_and_several_matrices_w_different_layouts(rng, tmp_path):
# several matrices
mats = [np.require(rng.random(size=(100, 2)), requirements=order) for order in ("C", "F", "F", "C")]
several_path = tmp_path / "several.txt"
lgb.Dataset(mats)._dump_text(several_path)
# one matrix
mat = np.vstack(mats)
one_path = tmp_path / "one.txt"
lgb.Dataset(mat)._dump_text(one_path)
assert filecmp.cmp(one_path, several_path)
@pytest.mark.parametrize(
"field_name",
[
"group",
"init_score",
pytest.param(
"position",
marks=pytest.mark.skipif(
BuildInfo.has_cuda,
reason="Positions in learning to rank is not supported in CUDA version yet",
),
),
"weight",
],
)
def test_set_field_none_removes_field(rng, field_name):
X = rng.uniform(size=(10, 1))
d = lgb.Dataset(X).construct()
if field_name == "group":
field = [5, 5]
expected = np.array([0, 5, 10], dtype=np.int32)
elif field_name == "position":
field = [100, 20, 100, 10, 30, 10, 30, 10, 30, 30]
expected = np.array([0, 1, 0, 2, 3, 2, 3, 2, 3, 3], dtype=np.int32)
else:
field = rng.uniform(size=10)
expected = field.astype(np.float64 if field_name == "init_score" else np.float32)
out = d.set_field(field_name, field)
assert out is d
np_assert_array_equal(d.get_field(field_name), expected, strict=True)
d.set_field(field_name, None)
assert d.get_field(field_name) is None
def test_booster_eval_adds_new_valid_dataset() -> None:
X_train, X_test, y_train, y_test = train_test_split(
*load_breast_cancer(return_X_y=True),
test_size=0.1,
random_state=42,
)
train_set = lgb.Dataset(X_train, label=y_train)
valid_set = lgb.Dataset(X_test, label=y_test, reference=train_set)
booster = lgb.Booster(
params={
"deterministic": True,
"force_row_wise": True,
"objective": "binary",
"metric": ["auc", "binary_error"],
"num_iterations": 2,
"num_leaves": 3,
"num_threads": 1,
"seed": 708,
"verbose": -1,
},
train_set=train_set,
)
assert booster._Booster__num_dataset == 1
assert booster.valid_sets == []
result = booster.eval(valid_set, name="test")
assert booster._Booster__num_dataset == 2
assert booster.valid_sets == [valid_set]
assert len(result) == 2
assert isinstance(result, list)
# first metric - AUC
dataset_name, metric_name, metric_value, maximize = result[0]
assert dataset_name == "test"
assert metric_name == "auc"
assert metric_value >= 0.50
assert maximize is True
# second metric - binary error
dataset_name, metric_name, metric_value, maximize = result[1]
assert dataset_name == "test"
assert metric_name == "binary_error"
assert metric_value >= 0.40
assert maximize is False
def test_refit_correctly_handles_categorical_features_in_params(rng) -> None:
rng = np.random.default_rng()
X = rng.integers(1, 10, size=(1_000, 3))
y = rng.uniform(size=(X.shape[0],))
# Dataset with 'categorical_feature" keyword arg
dtrain = lgb.Dataset(X, label=y, categorical_feature=[0, 2])
bst = lgb.train(
params={
"num_leaves": 7,
"verbose": -1,
},
train_set=dtrain,
num_boost_round=2,
)
# 'categorical_column' is correctly set in params
assert bst.params["categorical_column"] == [0, 2]
# refit() should not raise a warning
X_new = rng.integers(1, 10, size=(10, 3))
y_new = rng.uniform(size=(X_new.shape[0],))
with warnings.catch_warnings() as w:
warnings.simplefilter("always")
bst.refit(X_new, y_new)
if w:
assert not any(
re.search(r"has been found in .*params.* and will be ignored", str(warning.message)) for warning in w
)
# round-trip to and from a model string
loaded_bst = lgb.Booster(model_str=bst.model_to_string())
# that round-trip sets Booster.params to all model parameters, using the "main"
# ones, not any aliases
assert loaded_bst.params["categorical_feature"] == [0, 2]
assert "categorical_column" not in loaded_bst.params
# case 1: 'categorical_feature' keyword arg not passed
# result: should succeed and not warn
loaded_bst_new = loaded_bst.refit(X_new, y_new)
assert loaded_bst_new.params["categorical_column"] == [0, 2]
# case 2: 'categorical_feature' keyword arg passed, but identical to what's in params
# result: should succeed and not warn
with warnings.catch_warnings(record=True) as w:
warnings.simplefilter("always")
loaded_bst_new = loaded_bst.refit(X_new, y_new, categorical_feature=[0, 2])
assert loaded_bst_new.params["categorical_column"] == [0, 2]
if w:
assert not any(
re.search(r"has been found in .*params.* and will be ignored", str(warning.message)) for warning in w
)
# case 3: 'categorical_feature' keyword arg passed, different value
# result: informative error
with pytest.raises(
lgb.basic.LightGBMError,
match=re.escape("Using refit() to change which columns are treated as categorical is not supported"),
):
loaded_bst_new = loaded_bst.refit(X_new, y_new, categorical_feature=[0, 1])