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from __future__ import annotations
import gzip
import io
import pathlib
import tarfile
from typing import (
TYPE_CHECKING,
Any,
Callable,
)
import uuid
import zipfile
from pandas.compat import (
get_bz2_file,
get_lzma_file,
)
from pandas.compat._optional import import_optional_dependency
import pandas as pd
from pandas._testing.contexts import ensure_clean
if TYPE_CHECKING:
from pandas._typing import (
FilePath,
ReadPickleBuffer,
)
from pandas import (
DataFrame,
Series,
)
# ------------------------------------------------------------------
# File-IO
def round_trip_pickle(
obj: Any, path: FilePath | ReadPickleBuffer | None = None
) -> DataFrame | Series:
"""
Pickle an object and then read it again.
Parameters
----------
obj : any object
The object to pickle and then re-read.
path : str, path object or file-like object, default None
The path where the pickled object is written and then read.
Returns
-------
pandas object
The original object that was pickled and then re-read.
"""
_path = path
if _path is None:
_path = f"__{uuid.uuid4()}__.pickle"
with ensure_clean(_path) as temp_path:
pd.to_pickle(obj, temp_path)
return pd.read_pickle(temp_path)
def round_trip_pathlib(writer, reader, path: str | None = None):
"""
Write an object to file specified by a pathlib.Path and read it back
Parameters
----------
writer : callable bound to pandas object
IO writing function (e.g. DataFrame.to_csv )
reader : callable
IO reading function (e.g. pd.read_csv )
path : str, default None
The path where the object is written and then read.
Returns
-------
pandas object
The original object that was serialized and then re-read.
"""
Path = pathlib.Path
if path is None:
path = "___pathlib___"
with ensure_clean(path) as path:
writer(Path(path)) # type: ignore[arg-type]
obj = reader(Path(path)) # type: ignore[arg-type]
return obj
def round_trip_localpath(writer, reader, path: str | None = None):
"""
Write an object to file specified by a py.path LocalPath and read it back.
Parameters
----------
writer : callable bound to pandas object
IO writing function (e.g. DataFrame.to_csv )
reader : callable
IO reading function (e.g. pd.read_csv )
path : str, default None
The path where the object is written and then read.
Returns
-------
pandas object
The original object that was serialized and then re-read.
"""
import pytest
LocalPath = pytest.importorskip("py.path").local
if path is None:
path = "___localpath___"
with ensure_clean(path) as path:
writer(LocalPath(path))
obj = reader(LocalPath(path))
return obj
def write_to_compressed(compression, path, data, dest: str = "test") -> None:
"""
Write data to a compressed file.
Parameters
----------
compression : {'gzip', 'bz2', 'zip', 'xz', 'zstd'}
The compression type to use.
path : str
The file path to write the data.
data : str
The data to write.
dest : str, default "test"
The destination file (for ZIP only)
Raises
------
ValueError : An invalid compression value was passed in.
"""
args: tuple[Any, ...] = (data,)
mode = "wb"
method = "write"
compress_method: Callable
if compression == "zip":
compress_method = zipfile.ZipFile
mode = "w"
args = (dest, data)
method = "writestr"
elif compression == "tar":
compress_method = tarfile.TarFile
mode = "w"
file = tarfile.TarInfo(name=dest)
bytes = io.BytesIO(data)
file.size = len(data)
args = (file, bytes)
method = "addfile"
elif compression == "gzip":
compress_method = gzip.GzipFile
elif compression == "bz2":
compress_method = get_bz2_file()
elif compression == "zstd":
compress_method = import_optional_dependency("zstandard").open
elif compression == "xz":
compress_method = get_lzma_file()
else:
raise ValueError(f"Unrecognized compression type: {compression}")
with compress_method(path, mode=mode) as f:
getattr(f, method)(*args)
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