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import itertools
from dataclasses import dataclass
from typing import Optional
import pyarrow as pa
import datasets
from datasets.table import table_cast
logger = datasets.utils.logging.get_logger(__name__)
@dataclass
class ArrowConfig(datasets.BuilderConfig):
"""BuilderConfig for Arrow."""
features: Optional[datasets.Features] = None
def __post_init__(self):
super().__post_init__()
class Arrow(datasets.ArrowBasedBuilder):
BUILDER_CONFIG_CLASS = ArrowConfig
def _info(self):
return datasets.DatasetInfo(features=self.config.features)
def _split_generators(self, dl_manager):
"""We handle string, list and dicts in datafiles"""
if not self.config.data_files:
raise ValueError(f"At least one data file must be specified, but got data_files={self.config.data_files}")
dl_manager.download_config.extract_on_the_fly = True
data_files = dl_manager.download_and_extract(self.config.data_files)
splits = []
for split_name, files in data_files.items():
if isinstance(files, str):
files = [files]
# Use `dl_manager.iter_files` to skip hidden files in an extracted archive
files = [dl_manager.iter_files(file) for file in files]
# Infer features if they are stored in the arrow schema
if self.info.features is None:
for file in itertools.chain.from_iterable(files):
with open(file, "rb") as f:
try:
reader = pa.ipc.open_stream(f)
except (OSError, pa.lib.ArrowInvalid):
reader = pa.ipc.open_file(f)
self.info.features = datasets.Features.from_arrow_schema(reader.schema)
break
splits.append(datasets.SplitGenerator(name=split_name, gen_kwargs={"files": files}))
return splits
def _cast_table(self, pa_table: pa.Table) -> pa.Table:
if self.info.features is not None:
# more expensive cast to support nested features with keys in a different order
# allows str <-> int/float or str to Audio for example
pa_table = table_cast(pa_table, self.info.features.arrow_schema)
return pa_table
def _generate_tables(self, files):
for file_idx, file in enumerate(itertools.chain.from_iterable(files)):
with open(file, "rb") as f:
try:
try:
batches = pa.ipc.open_stream(f)
except (OSError, pa.lib.ArrowInvalid):
reader = pa.ipc.open_file(f)
batches = (reader.get_batch(i) for i in range(reader.num_record_batches))
for batch_idx, record_batch in enumerate(batches):
pa_table = pa.Table.from_batches([record_batch])
# Uncomment for debugging (will print the Arrow table size and elements)
# logger.warning(f"pa_table: {pa_table} num rows: {pa_table.num_rows}")
# logger.warning('\n'.join(str(pa_table.slice(i, 1).to_pydict()) for i in range(pa_table.num_rows)))
yield f"{file_idx}_{batch_idx}", self._cast_table(pa_table)
except ValueError as e:
logger.error(f"Failed to read file '{file}' with error {type(e)}: {e}")
raise
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