510 行
17 KiB
Python
510 行
17 KiB
Python
""" parquet compat """
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from __future__ import annotations
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import io
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import os
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from typing import Any
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from warnings import catch_warnings
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from pandas._typing import (
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FilePath,
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ReadBuffer,
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StorageOptions,
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WriteBuffer,
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)
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from pandas.compat._optional import import_optional_dependency
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from pandas.errors import AbstractMethodError
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from pandas.util._decorators import doc
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from pandas import (
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DataFrame,
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MultiIndex,
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get_option,
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)
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from pandas.core.shared_docs import _shared_docs
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from pandas.util.version import Version
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from pandas.io.common import (
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IOHandles,
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get_handle,
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is_fsspec_url,
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is_url,
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stringify_path,
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)
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def get_engine(engine: str) -> BaseImpl:
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"""return our implementation"""
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if engine == "auto":
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engine = get_option("io.parquet.engine")
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if engine == "auto":
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# try engines in this order
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engine_classes = [PyArrowImpl, FastParquetImpl]
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error_msgs = ""
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for engine_class in engine_classes:
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try:
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return engine_class()
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except ImportError as err:
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error_msgs += "\n - " + str(err)
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raise ImportError(
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"Unable to find a usable engine; "
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"tried using: 'pyarrow', 'fastparquet'.\n"
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"A suitable version of "
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"pyarrow or fastparquet is required for parquet "
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"support.\n"
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"Trying to import the above resulted in these errors:"
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f"{error_msgs}"
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)
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if engine == "pyarrow":
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return PyArrowImpl()
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elif engine == "fastparquet":
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return FastParquetImpl()
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raise ValueError("engine must be one of 'pyarrow', 'fastparquet'")
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def _get_path_or_handle(
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path: FilePath | ReadBuffer[bytes] | WriteBuffer[bytes],
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fs: Any,
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storage_options: StorageOptions = None,
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mode: str = "rb",
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is_dir: bool = False,
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) -> tuple[
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FilePath | ReadBuffer[bytes] | WriteBuffer[bytes], IOHandles[bytes] | None, Any
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]:
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"""File handling for PyArrow."""
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path_or_handle = stringify_path(path)
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if is_fsspec_url(path_or_handle) and fs is None:
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fsspec = import_optional_dependency("fsspec")
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fs, path_or_handle = fsspec.core.url_to_fs(
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path_or_handle, **(storage_options or {})
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)
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elif storage_options and (not is_url(path_or_handle) or mode != "rb"):
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# can't write to a remote url
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# without making use of fsspec at the moment
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raise ValueError("storage_options passed with buffer, or non-supported URL")
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handles = None
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if (
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not fs
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and not is_dir
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and isinstance(path_or_handle, str)
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and not os.path.isdir(path_or_handle)
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):
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# use get_handle only when we are very certain that it is not a directory
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# fsspec resources can also point to directories
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# this branch is used for example when reading from non-fsspec URLs
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handles = get_handle(
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path_or_handle, mode, is_text=False, storage_options=storage_options
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)
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fs = None
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path_or_handle = handles.handle
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return path_or_handle, handles, fs
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class BaseImpl:
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@staticmethod
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def validate_dataframe(df: DataFrame) -> None:
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if not isinstance(df, DataFrame):
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raise ValueError("to_parquet only supports IO with DataFrames")
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# must have value column names for all index levels (strings only)
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if isinstance(df.columns, MultiIndex):
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if not all(
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x.inferred_type in {"string", "empty"} for x in df.columns.levels
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):
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raise ValueError(
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"""
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parquet must have string column names for all values in
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each level of the MultiIndex
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"""
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)
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else:
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if df.columns.inferred_type not in {"string", "empty"}:
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raise ValueError("parquet must have string column names")
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# index level names must be strings
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valid_names = all(
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isinstance(name, str) for name in df.index.names if name is not None
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)
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if not valid_names:
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raise ValueError("Index level names must be strings")
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def write(self, df: DataFrame, path, compression, **kwargs):
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raise AbstractMethodError(self)
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def read(self, path, columns=None, **kwargs) -> DataFrame:
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raise AbstractMethodError(self)
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class PyArrowImpl(BaseImpl):
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def __init__(self) -> None:
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import_optional_dependency(
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"pyarrow", extra="pyarrow is required for parquet support."
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)
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import pyarrow.parquet
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# import utils to register the pyarrow extension types
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import pandas.core.arrays.arrow.extension_types # pyright: ignore # noqa:F401
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self.api = pyarrow
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def write(
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self,
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df: DataFrame,
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path: FilePath | WriteBuffer[bytes],
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compression: str | None = "snappy",
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index: bool | None = None,
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storage_options: StorageOptions = None,
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partition_cols: list[str] | None = None,
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**kwargs,
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) -> None:
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self.validate_dataframe(df)
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from_pandas_kwargs: dict[str, Any] = {"schema": kwargs.pop("schema", None)}
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if index is not None:
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from_pandas_kwargs["preserve_index"] = index
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table = self.api.Table.from_pandas(df, **from_pandas_kwargs)
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path_or_handle, handles, kwargs["filesystem"] = _get_path_or_handle(
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path,
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kwargs.pop("filesystem", None),
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storage_options=storage_options,
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mode="wb",
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is_dir=partition_cols is not None,
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)
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if (
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isinstance(path_or_handle, io.BufferedWriter)
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and hasattr(path_or_handle, "name")
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and isinstance(path_or_handle.name, (str, bytes))
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):
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path_or_handle = path_or_handle.name
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if isinstance(path_or_handle, bytes):
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path_or_handle = path_or_handle.decode()
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try:
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if partition_cols is not None:
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# writes to multiple files under the given path
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self.api.parquet.write_to_dataset(
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table,
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path_or_handle,
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compression=compression,
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partition_cols=partition_cols,
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**kwargs,
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)
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else:
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# write to single output file
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self.api.parquet.write_table(
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table, path_or_handle, compression=compression, **kwargs
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)
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finally:
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if handles is not None:
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handles.close()
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def read(
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self,
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path,
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columns=None,
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use_nullable_dtypes=False,
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storage_options: StorageOptions = None,
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**kwargs,
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) -> DataFrame:
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kwargs["use_pandas_metadata"] = True
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to_pandas_kwargs = {}
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if use_nullable_dtypes:
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import pandas as pd
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mapping = {
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self.api.int8(): pd.Int8Dtype(),
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self.api.int16(): pd.Int16Dtype(),
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self.api.int32(): pd.Int32Dtype(),
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self.api.int64(): pd.Int64Dtype(),
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self.api.uint8(): pd.UInt8Dtype(),
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self.api.uint16(): pd.UInt16Dtype(),
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self.api.uint32(): pd.UInt32Dtype(),
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self.api.uint64(): pd.UInt64Dtype(),
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self.api.bool_(): pd.BooleanDtype(),
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self.api.string(): pd.StringDtype(),
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self.api.float32(): pd.Float32Dtype(),
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self.api.float64(): pd.Float64Dtype(),
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}
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to_pandas_kwargs["types_mapper"] = mapping.get
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manager = get_option("mode.data_manager")
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if manager == "array":
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to_pandas_kwargs["split_blocks"] = True # type: ignore[assignment]
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path_or_handle, handles, kwargs["filesystem"] = _get_path_or_handle(
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path,
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kwargs.pop("filesystem", None),
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storage_options=storage_options,
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mode="rb",
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)
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try:
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result = self.api.parquet.read_table(
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path_or_handle, columns=columns, **kwargs
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).to_pandas(**to_pandas_kwargs)
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if manager == "array":
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result = result._as_manager("array", copy=False)
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return result
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finally:
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if handles is not None:
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handles.close()
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class FastParquetImpl(BaseImpl):
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def __init__(self) -> None:
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# since pandas is a dependency of fastparquet
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# we need to import on first use
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fastparquet = import_optional_dependency(
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"fastparquet", extra="fastparquet is required for parquet support."
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)
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self.api = fastparquet
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def write(
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self,
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df: DataFrame,
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path,
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compression="snappy",
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index=None,
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partition_cols=None,
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storage_options: StorageOptions = None,
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**kwargs,
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) -> None:
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self.validate_dataframe(df)
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# thriftpy/protocol/compact.py:339:
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# DeprecationWarning: tostring() is deprecated.
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# Use tobytes() instead.
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if "partition_on" in kwargs and partition_cols is not None:
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raise ValueError(
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"Cannot use both partition_on and "
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"partition_cols. Use partition_cols for partitioning data"
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)
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elif "partition_on" in kwargs:
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partition_cols = kwargs.pop("partition_on")
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if partition_cols is not None:
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kwargs["file_scheme"] = "hive"
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# cannot use get_handle as write() does not accept file buffers
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path = stringify_path(path)
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if is_fsspec_url(path):
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fsspec = import_optional_dependency("fsspec")
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# if filesystem is provided by fsspec, file must be opened in 'wb' mode.
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kwargs["open_with"] = lambda path, _: fsspec.open(
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path, "wb", **(storage_options or {})
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).open()
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elif storage_options:
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raise ValueError(
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"storage_options passed with file object or non-fsspec file path"
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)
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with catch_warnings(record=True):
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self.api.write(
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path,
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df,
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compression=compression,
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write_index=index,
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partition_on=partition_cols,
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**kwargs,
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)
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def read(
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self, path, columns=None, storage_options: StorageOptions = None, **kwargs
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) -> DataFrame:
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parquet_kwargs: dict[str, Any] = {}
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use_nullable_dtypes = kwargs.pop("use_nullable_dtypes", False)
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if Version(self.api.__version__) >= Version("0.7.1"):
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# We are disabling nullable dtypes for fastparquet pending discussion
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parquet_kwargs["pandas_nulls"] = False
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if use_nullable_dtypes:
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raise ValueError(
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"The 'use_nullable_dtypes' argument is not supported for the "
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"fastparquet engine"
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)
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path = stringify_path(path)
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handles = None
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if is_fsspec_url(path):
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fsspec = import_optional_dependency("fsspec")
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if Version(self.api.__version__) > Version("0.6.1"):
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parquet_kwargs["fs"] = fsspec.open(
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path, "rb", **(storage_options or {})
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).fs
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else:
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parquet_kwargs["open_with"] = lambda path, _: fsspec.open(
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path, "rb", **(storage_options or {})
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).open()
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elif isinstance(path, str) and not os.path.isdir(path):
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# use get_handle only when we are very certain that it is not a directory
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# fsspec resources can also point to directories
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# this branch is used for example when reading from non-fsspec URLs
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handles = get_handle(
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path, "rb", is_text=False, storage_options=storage_options
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)
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path = handles.handle
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try:
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parquet_file = self.api.ParquetFile(path, **parquet_kwargs)
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return parquet_file.to_pandas(columns=columns, **kwargs)
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finally:
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if handles is not None:
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handles.close()
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@doc(storage_options=_shared_docs["storage_options"])
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def to_parquet(
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df: DataFrame,
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path: FilePath | WriteBuffer[bytes] | None = None,
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engine: str = "auto",
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compression: str | None = "snappy",
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index: bool | None = None,
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storage_options: StorageOptions = None,
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partition_cols: list[str] | None = None,
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**kwargs,
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) -> bytes | None:
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"""
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Write a DataFrame to the parquet format.
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Parameters
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----------
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df : DataFrame
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path : str, path object, file-like object, or None, default None
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String, path object (implementing ``os.PathLike[str]``), or file-like
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object implementing a binary ``write()`` function. If None, the result is
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returned as bytes. If a string, it will be used as Root Directory path
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when writing a partitioned dataset. The engine fastparquet does not
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accept file-like objects.
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.. versionchanged:: 1.2.0
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engine : {{'auto', 'pyarrow', 'fastparquet'}}, default 'auto'
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Parquet library to use. If 'auto', then the option
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``io.parquet.engine`` is used. The default ``io.parquet.engine``
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behavior is to try 'pyarrow', falling back to 'fastparquet' if
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'pyarrow' is unavailable.
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compression : {{'snappy', 'gzip', 'brotli', 'lz4', 'zstd', None}},
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default 'snappy'. Name of the compression to use. Use ``None``
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for no compression. The supported compression methods actually
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depend on which engine is used. For 'pyarrow', 'snappy', 'gzip',
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'brotli', 'lz4', 'zstd' are all supported. For 'fastparquet',
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only 'gzip' and 'snappy' are supported.
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index : bool, default None
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If ``True``, include the dataframe's index(es) in the file output. If
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``False``, they will not be written to the file.
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If ``None``, similar to ``True`` the dataframe's index(es)
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will be saved. However, instead of being saved as values,
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the RangeIndex will be stored as a range in the metadata so it
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doesn't require much space and is faster. Other indexes will
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be included as columns in the file output.
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partition_cols : str or list, optional, default None
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Column names by which to partition the dataset.
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Columns are partitioned in the order they are given.
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Must be None if path is not a string.
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{storage_options}
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.. versionadded:: 1.2.0
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kwargs
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Additional keyword arguments passed to the engine
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Returns
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-------
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bytes if no path argument is provided else None
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"""
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if isinstance(partition_cols, str):
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partition_cols = [partition_cols]
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impl = get_engine(engine)
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path_or_buf: FilePath | WriteBuffer[bytes] = io.BytesIO() if path is None else path
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impl.write(
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df,
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path_or_buf,
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compression=compression,
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index=index,
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partition_cols=partition_cols,
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storage_options=storage_options,
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**kwargs,
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)
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if path is None:
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assert isinstance(path_or_buf, io.BytesIO)
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return path_or_buf.getvalue()
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else:
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return None
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@doc(storage_options=_shared_docs["storage_options"])
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def read_parquet(
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path: FilePath | ReadBuffer[bytes],
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engine: str = "auto",
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columns: list[str] | None = None,
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storage_options: StorageOptions = None,
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use_nullable_dtypes: bool = False,
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**kwargs,
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) -> DataFrame:
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"""
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Load a parquet object from the file path, returning a DataFrame.
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Parameters
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----------
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path : str, path object or file-like object
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String, path object (implementing ``os.PathLike[str]``), or file-like
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object implementing a binary ``read()`` function.
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The string could be a URL. Valid URL schemes include http, ftp, s3,
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gs, and file. For file URLs, a host is expected. A local file could be:
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``file://localhost/path/to/table.parquet``.
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A file URL can also be a path to a directory that contains multiple
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partitioned parquet files. Both pyarrow and fastparquet support
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paths to directories as well as file URLs. A directory path could be:
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``file://localhost/path/to/tables`` or ``s3://bucket/partition_dir``.
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engine : {{'auto', 'pyarrow', 'fastparquet'}}, default 'auto'
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Parquet library to use. If 'auto', then the option
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``io.parquet.engine`` is used. The default ``io.parquet.engine``
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behavior is to try 'pyarrow', falling back to 'fastparquet' if
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'pyarrow' is unavailable.
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columns : list, default=None
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If not None, only these columns will be read from the file.
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{storage_options}
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.. versionadded:: 1.3.0
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use_nullable_dtypes : bool, default False
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If True, use dtypes that use ``pd.NA`` as missing value indicator
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for the resulting DataFrame. (only applicable for the ``pyarrow``
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engine)
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As new dtypes are added that support ``pd.NA`` in the future, the
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output with this option will change to use those dtypes.
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Note: this is an experimental option, and behaviour (e.g. additional
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support dtypes) may change without notice.
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.. versionadded:: 1.2.0
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**kwargs
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Any additional kwargs are passed to the engine.
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Returns
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-------
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DataFrame
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"""
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impl = get_engine(engine)
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return impl.read(
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path,
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columns=columns,
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storage_options=storage_options,
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use_nullable_dtypes=use_nullable_dtypes,
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**kwargs,
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)
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