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ray-project--ray/doc/source/train/doc_code/lightgbm_quickstart.py
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2026-07-13 13:17:40 +08:00

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Python

# flake8: noqa
# isort: skip_file
# __lightgbm_start__
import pandas as pd
import lightgbm as lgb
# 1. Load your data as a `lightgbm.Dataset`.
train_df = pd.read_csv("s3://ray-example-data/iris/train/1.csv")
eval_df = pd.read_csv("s3://ray-example-data/iris/val/1.csv")
train_X = train_df.drop("target", axis=1)
train_y = train_df["target"]
eval_X = eval_df.drop("target", axis=1)
eval_y = eval_df["target"]
train_set = lgb.Dataset(train_X, label=train_y)
eval_set = lgb.Dataset(eval_X, label=eval_y)
# 2. Define your LightGBM model training parameters.
params = {
"objective": "multiclass",
"num_class": 3,
"metric": ["multi_logloss", "multi_error"],
"verbosity": -1,
"boosting_type": "gbdt",
"num_leaves": 31,
"learning_rate": 0.05,
"feature_fraction": 0.9,
"bagging_fraction": 0.8,
"bagging_freq": 5,
}
# 3. Do non-distributed training.
model = lgb.train(
params,
train_set,
valid_sets=[eval_set],
valid_names=["eval"],
num_boost_round=100,
)
# __lightgbm_end__
# __lightgbm_ray_start__
import lightgbm as lgb
import ray.train
from ray.train.lightgbm import LightGBMTrainer, RayTrainReportCallback
# 1. Load your data as a Ray Data Dataset.
train_dataset = ray.data.read_csv("s3://anonymous@ray-example-data/iris/train")
eval_dataset = ray.data.read_csv("s3://anonymous@ray-example-data/iris/val")
def train_func():
# 2. Load your data shard as a `lightgbm.Dataset`.
# Get dataset shards for this worker
train_shard = ray.train.get_dataset_shard("train")
eval_shard = ray.train.get_dataset_shard("eval")
# Convert shards to PyArrow tables. LightGBM (>=4.2.0) supports PyArrow
# natively, which avoids a round-trip through pandas.
import pyarrow as pa
train_table = pa.concat_tables(
train_shard.iter_batches(batch_format="pyarrow", batch_size=None)
)
eval_table = pa.concat_tables(
eval_shard.iter_batches(batch_format="pyarrow", batch_size=None)
)
train_X = train_table.drop(["target"])
train_y = train_table.column("target")
eval_X = eval_table.drop(["target"])
eval_y = eval_table.column("target")
train_set = lgb.Dataset(train_X, label=train_y)
eval_set = lgb.Dataset(eval_X, label=eval_y)
# 3. Define your LightGBM model training parameters.
params = {
"objective": "multiclass",
"num_class": 3,
"metric": ["multi_logloss", "multi_error"],
"verbosity": -1,
"boosting_type": "gbdt",
"num_leaves": 31,
"learning_rate": 0.05,
"feature_fraction": 0.9,
"bagging_fraction": 0.8,
"bagging_freq": 5,
# Adding the lines below are the only changes needed
# for your `lgb.train` call!
"tree_learner": "data_parallel",
"pre_partition": True,
**ray.train.lightgbm.get_network_params(),
}
# 4. Do distributed data-parallel training.
# Ray Train sets up the necessary coordinator processes and
# environment variables for your workers to communicate with each other.
model = lgb.train(
params,
train_set,
valid_sets=[eval_set],
valid_names=["eval"],
num_boost_round=100,
# Optional: Use the `RayTrainReportCallback` to save and report checkpoints.
callbacks=[RayTrainReportCallback()],
)
# 5. Configure scaling and resource requirements.
scaling_config = ray.train.ScalingConfig(num_workers=2, resources_per_worker={"CPU": 2})
# 6. Launch distributed training job.
trainer = LightGBMTrainer(
train_func,
scaling_config=scaling_config,
datasets={"train": train_dataset, "eval": eval_dataset},
)
result = trainer.fit()
# 7. Load the trained model.
model = RayTrainReportCallback.get_model(result.checkpoint)
# __lightgbm_ray_end__