462 lines
16 KiB
Python
462 lines
16 KiB
Python
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""" parquet compat """
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from distutils.version import LooseVersion
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import io
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import os
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from typing import Any, AnyStr, Dict, List, Optional, Tuple
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from warnings import catch_warnings
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from pandas._typing import FilePathOrBuffer, StorageOptions
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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 DataFrame, MultiIndex, get_option
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from pandas.core import generic
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from pandas.io.common import IOHandles, get_handle, is_fsspec_url, stringify_path
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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: FilePathOrBuffer,
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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[FilePathOrBuffer, Optional[IOHandles], Any]:
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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:
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raise ValueError("storage_options passed with buffer or non-fsspec filepath")
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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(path_or_handle, mode, is_text=False)
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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):
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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):
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raise AbstractMethodError(self)
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class PyArrowImpl(BaseImpl):
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def __init__(self):
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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_utils # noqa
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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: FilePathOrBuffer[AnyStr],
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compression: Optional[str] = "snappy",
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index: Optional[bool] = None,
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storage_options: StorageOptions = None,
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partition_cols: Optional[List[str]] = None,
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**kwargs,
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):
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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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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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):
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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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if LooseVersion(self.api.__version__) >= "0.16":
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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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}
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to_pandas_kwargs["types_mapper"] = mapping.get
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else:
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raise ValueError(
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"'use_nullable_dtypes=True' is only supported for pyarrow >= 0.16 "
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f"({self.api.__version__} is installed"
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)
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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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return 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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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):
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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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):
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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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):
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use_nullable_dtypes = kwargs.pop("use_nullable_dtypes", 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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parquet_kwargs = {}
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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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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(path, "rb", is_text=False)
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path = handles.handle
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parquet_file = self.api.ParquetFile(path, **parquet_kwargs)
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result = parquet_file.to_pandas(columns=columns, **kwargs)
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if handles is not None:
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handles.close()
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return result
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@doc(storage_options=generic._shared_docs["storage_options"])
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def to_parquet(
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df: DataFrame,
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path: Optional[FilePathOrBuffer] = None,
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engine: str = "auto",
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compression: Optional[str] = "snappy",
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index: Optional[bool] = None,
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storage_options: StorageOptions = None,
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partition_cols: Optional[List[str]] = None,
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**kwargs,
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) -> Optional[bytes]:
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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 or file-like object, default None
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If a string, it will be used as Root Directory path
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when writing a partitioned dataset. By file-like object,
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we refer to objects with a write() method, such as a file handle
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(e.g. via builtin open function) or io.BytesIO. The engine
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fastparquet does not accept file-like objects. If path is None,
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a bytes object is returned.
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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', None}}, default 'snappy'
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Name of the compression to use. Use ``None`` for no compression.
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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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.. versionadded:: 0.24.0
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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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.. versionadded:: 0.24.0
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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):
|
||
|
|
partition_cols = [partition_cols]
|
||
|
|
impl = get_engine(engine)
|
||
|
|
|
||
|
|
path_or_buf: FilePathOrBuffer = io.BytesIO() if path is None else path
|
||
|
|
|
||
|
|
impl.write(
|
||
|
|
df,
|
||
|
|
path_or_buf,
|
||
|
|
compression=compression,
|
||
|
|
index=index,
|
||
|
|
partition_cols=partition_cols,
|
||
|
|
storage_options=storage_options,
|
||
|
|
**kwargs,
|
||
|
|
)
|
||
|
|
|
||
|
|
if path is None:
|
||
|
|
assert isinstance(path_or_buf, io.BytesIO)
|
||
|
|
return path_or_buf.getvalue()
|
||
|
|
else:
|
||
|
|
return None
|
||
|
|
|
||
|
|
|
||
|
|
def read_parquet(
|
||
|
|
path,
|
||
|
|
engine: str = "auto",
|
||
|
|
columns=None,
|
||
|
|
use_nullable_dtypes: bool = False,
|
||
|
|
**kwargs,
|
||
|
|
):
|
||
|
|
"""
|
||
|
|
Load a parquet object from the file path, returning a DataFrame.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
path : str, path object or file-like object
|
||
|
|
Any valid string path is acceptable. The string could be a URL. Valid
|
||
|
|
URL schemes include http, ftp, s3, gs, and file. For file URLs, a host is
|
||
|
|
expected. A local file could be:
|
||
|
|
``file://localhost/path/to/table.parquet``.
|
||
|
|
A file URL can also be a path to a directory that contains multiple
|
||
|
|
partitioned parquet files. Both pyarrow and fastparquet support
|
||
|
|
paths to directories as well as file URLs. A directory path could be:
|
||
|
|
``file://localhost/path/to/tables`` or ``s3://bucket/partition_dir``
|
||
|
|
|
||
|
|
If you want to pass in a path object, pandas accepts any
|
||
|
|
``os.PathLike``.
|
||
|
|
|
||
|
|
By file-like object, we refer to objects with a ``read()`` method,
|
||
|
|
such as a file handle (e.g. via builtin ``open`` function)
|
||
|
|
or ``StringIO``.
|
||
|
|
engine : {'auto', 'pyarrow', 'fastparquet'}, default 'auto'
|
||
|
|
Parquet library to use. If 'auto', then the option
|
||
|
|
``io.parquet.engine`` is used. The default ``io.parquet.engine``
|
||
|
|
behavior is to try 'pyarrow', falling back to 'fastparquet' if
|
||
|
|
'pyarrow' is unavailable.
|
||
|
|
columns : list, default=None
|
||
|
|
If not None, only these columns will be read from the file.
|
||
|
|
use_nullable_dtypes : bool, default False
|
||
|
|
If True, use dtypes that use ``pd.NA`` as missing value indicator
|
||
|
|
for the resulting DataFrame (only applicable for ``engine="pyarrow"``).
|
||
|
|
As new dtypes are added that support ``pd.NA`` in the future, the
|
||
|
|
output with this option will change to use those dtypes.
|
||
|
|
Note: this is an experimental option, and behaviour (e.g. additional
|
||
|
|
support dtypes) may change without notice.
|
||
|
|
|
||
|
|
.. versionadded:: 1.2.0
|
||
|
|
**kwargs
|
||
|
|
Any additional kwargs are passed to the engine.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
DataFrame
|
||
|
|
"""
|
||
|
|
impl = get_engine(engine)
|
||
|
|
return impl.read(
|
||
|
|
path, columns=columns, use_nullable_dtypes=use_nullable_dtypes, **kwargs
|
||
|
|
)
|