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pickle.py
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pickle.py
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""" pickle compat """
import warnings
import numpy as np
from numpy.lib.format import read_array, write_array
from pandas.compat import PY3, BytesIO, cPickle as pkl, pickle_compat as pc
from pandas.io.common import _get_handle, _stringify_path
def to_pickle(obj, path, compression='infer', protocol=pkl.HIGHEST_PROTOCOL):
"""
Pickle (serialize) object to file.
Parameters
----------
obj : any object
Any python object.
path : str
File path where the pickled object will be stored.
compression : {'infer', 'gzip', 'bz2', 'zip', 'xz', None}, default 'infer'
A string representing the compression to use in the output file. By
default, infers from the file extension in specified path.
.. versionadded:: 0.20.0
protocol : int
Int which indicates which protocol should be used by the pickler,
default HIGHEST_PROTOCOL (see [1], paragraph 12.1.2). The possible
values for this parameter depend on the version of Python. For Python
2.x, possible values are 0, 1, 2. For Python>=3.0, 3 is a valid value.
For Python >= 3.4, 4 is a valid value. A negative value for the
protocol parameter is equivalent to setting its value to
HIGHEST_PROTOCOL.
.. [1] https://docs.python.org/3/library/pickle.html
.. versionadded:: 0.21.0
See Also
--------
read_pickle : Load pickled pandas object (or any object) from file.
DataFrame.to_hdf : Write DataFrame to an HDF5 file.
DataFrame.to_sql : Write DataFrame to a SQL database.
DataFrame.to_parquet : Write a DataFrame to the binary parquet format.
Examples
--------
>>> original_df = pd.DataFrame({"foo": range(5), "bar": range(5, 10)})
>>> original_df
foo bar
0 0 5
1 1 6
2 2 7
3 3 8
4 4 9
>>> pd.to_pickle(original_df, "./dummy.pkl")
>>> unpickled_df = pd.read_pickle("./dummy.pkl")
>>> unpickled_df
foo bar
0 0 5
1 1 6
2 2 7
3 3 8
4 4 9
>>> import os
>>> os.remove("./dummy.pkl")
"""
path = _stringify_path(path)
f, fh = _get_handle(path, 'wb',
compression=compression,
is_text=False)
if protocol < 0:
protocol = pkl.HIGHEST_PROTOCOL
try:
f.write(pkl.dumps(obj, protocol=protocol))
finally:
for _f in fh:
_f.close()
def read_pickle(path, compression='infer'):
"""
Load pickled pandas object (or any object) from file.
.. warning::
Loading pickled data received from untrusted sources can be
unsafe. See `here <https://docs.python.org/3/library/pickle.html>`__.
Parameters
----------
path : str
File path where the pickled object will be loaded.
compression : {'infer', 'gzip', 'bz2', 'zip', 'xz', None}, default 'infer'
For on-the-fly decompression of on-disk data. If 'infer', then use
gzip, bz2, xz or zip if path ends in '.gz', '.bz2', '.xz',
or '.zip' respectively, and no decompression otherwise.
Set to None for no decompression.
.. versionadded:: 0.20.0
Returns
-------
unpickled : same type as object stored in file
See Also
--------
DataFrame.to_pickle : Pickle (serialize) DataFrame object to file.
Series.to_pickle : Pickle (serialize) Series object to file.
read_hdf : Read HDF5 file into a DataFrame.
read_sql : Read SQL query or database table into a DataFrame.
read_parquet : Load a parquet object, returning a DataFrame.
Examples
--------
>>> original_df = pd.DataFrame({"foo": range(5), "bar": range(5, 10)})
>>> original_df
foo bar
0 0 5
1 1 6
2 2 7
3 3 8
4 4 9
>>> pd.to_pickle(original_df, "./dummy.pkl")
>>> unpickled_df = pd.read_pickle("./dummy.pkl")
>>> unpickled_df
foo bar
0 0 5
1 1 6
2 2 7
3 3 8
4 4 9
>>> import os
>>> os.remove("./dummy.pkl")
"""
path = _stringify_path(path)
def read_wrapper(func):
# wrapper file handle open/close operation
f, fh = _get_handle(path, 'rb',
compression=compression,
is_text=False)
try:
return func(f)
finally:
for _f in fh:
_f.close()
def try_read(path, encoding=None):
# try with cPickle
# try with current pickle, if we have a Type Error then
# try with the compat pickle to handle subclass changes
# pass encoding only if its not None as py2 doesn't handle
# the param
# cpickle
# GH 6899
try:
with warnings.catch_warnings(record=True):
# We want to silence any warnings about, e.g. moved modules.
warnings.simplefilter("ignore", Warning)
return read_wrapper(lambda f: pkl.load(f))
except Exception: # noqa: E722
# reg/patched pickle
# compat not used in pandas/compat/pickle_compat.py::load
# TODO: remove except block OR modify pc.load to use compat
try:
return read_wrapper(
lambda f: pc.load(f, encoding=encoding, compat=False))
# compat pickle
except Exception: # noqa: E722
return read_wrapper(
lambda f: pc.load(f, encoding=encoding, compat=True))
try:
return try_read(path)
except Exception: # noqa: E722
if PY3:
return try_read(path, encoding='latin1')
raise
# compat with sparse pickle / unpickle
def _pickle_array(arr):
arr = arr.view(np.ndarray)
buf = BytesIO()
write_array(buf, arr)
return buf.getvalue()
def _unpickle_array(bytes):
arr = read_array(BytesIO(bytes))
return arr