120 lines
3.5 KiB
Python
120 lines
3.5 KiB
Python
""" feather-format compat """
|
|
|
|
from distutils.version import LooseVersion
|
|
|
|
from pandas.compat._optional import import_optional_dependency
|
|
from pandas.util._decorators import deprecate_kwarg
|
|
|
|
from pandas import DataFrame, Int64Index, RangeIndex
|
|
|
|
from pandas.io.common import _stringify_path
|
|
|
|
|
|
def to_feather(df, path):
|
|
"""
|
|
Write a DataFrame to the feather-format
|
|
|
|
Parameters
|
|
----------
|
|
df : DataFrame
|
|
path : string file path, or file-like object
|
|
|
|
"""
|
|
import_optional_dependency("pyarrow")
|
|
from pyarrow import feather
|
|
|
|
path = _stringify_path(path)
|
|
|
|
if not isinstance(df, DataFrame):
|
|
raise ValueError("feather only support IO with DataFrames")
|
|
|
|
valid_types = {"string", "unicode"}
|
|
|
|
# validate index
|
|
# --------------
|
|
|
|
# validate that we have only a default index
|
|
# raise on anything else as we don't serialize the index
|
|
|
|
if not isinstance(df.index, Int64Index):
|
|
raise ValueError(
|
|
"feather does not support serializing {} "
|
|
"for the index; you can .reset_index()"
|
|
"to make the index into column(s)".format(type(df.index))
|
|
)
|
|
|
|
if not df.index.equals(RangeIndex.from_range(range(len(df)))):
|
|
raise ValueError(
|
|
"feather does not support serializing a "
|
|
"non-default index for the index; you "
|
|
"can .reset_index() to make the index "
|
|
"into column(s)"
|
|
)
|
|
|
|
if df.index.name is not None:
|
|
raise ValueError(
|
|
"feather does not serialize index meta-data on a " "default index"
|
|
)
|
|
|
|
# validate columns
|
|
# ----------------
|
|
|
|
# must have value column names (strings only)
|
|
if df.columns.inferred_type not in valid_types:
|
|
raise ValueError("feather must have string column names")
|
|
|
|
feather.write_feather(df, path)
|
|
|
|
|
|
@deprecate_kwarg(old_arg_name="nthreads", new_arg_name="use_threads")
|
|
def read_feather(path, columns=None, use_threads=True):
|
|
"""
|
|
Load a feather-format object from the file path.
|
|
|
|
.. versionadded 0.20.0
|
|
|
|
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, and file. For file URLs, a host is
|
|
expected. A local file could be:
|
|
``file://localhost/path/to/table.feather``.
|
|
|
|
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 handler (e.g. via builtin ``open`` function)
|
|
or ``StringIO``.
|
|
columns : sequence, default None
|
|
If not provided, all columns are read.
|
|
|
|
.. versionadded 0.24.0
|
|
nthreads : int, default 1
|
|
Number of CPU threads to use when reading to pandas.DataFrame.
|
|
|
|
.. versionadded 0.21.0
|
|
.. deprecated 0.24.0
|
|
use_threads : bool, default True
|
|
Whether to parallelize reading using multiple threads.
|
|
|
|
.. versionadded 0.24.0
|
|
|
|
Returns
|
|
-------
|
|
type of object stored in file
|
|
"""
|
|
pyarrow = import_optional_dependency("pyarrow")
|
|
from pyarrow import feather
|
|
|
|
path = _stringify_path(path)
|
|
|
|
if LooseVersion(pyarrow.__version__) < LooseVersion("0.11.0"):
|
|
int_use_threads = int(use_threads)
|
|
if int_use_threads < 1:
|
|
int_use_threads = 1
|
|
return feather.read_feather(path, columns=columns, nthreads=int_use_threads)
|
|
|
|
return feather.read_feather(path, columns=columns, use_threads=bool(use_threads))
|