205 lines
6.1 KiB
Python
205 lines
6.1 KiB
Python
""" pickle compat """
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import warnings
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import numpy as np
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from numpy.lib.format import read_array, write_array
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from pandas.compat import BytesIO, cPickle as pkl, pickle_compat as pc, PY3
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from pandas.core.dtypes.common import is_datetime64_dtype, _NS_DTYPE
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from pandas.io.common import _get_handle, _infer_compression, _stringify_path
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def to_pickle(obj, path, compression='infer', protocol=pkl.HIGHEST_PROTOCOL):
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"""
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Pickle (serialize) object to file.
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Parameters
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----------
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obj : any object
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Any python object.
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path : str
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File path where the pickled object will be stored.
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compression : {'infer', 'gzip', 'bz2', 'zip', 'xz', None}, default 'infer'
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A string representing the compression to use in the output file. By
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default, infers from the file extension in specified path.
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.. versionadded:: 0.20.0
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protocol : int
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Int which indicates which protocol should be used by the pickler,
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default HIGHEST_PROTOCOL (see [1], paragraph 12.1.2). The possible
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values for this parameter depend on the version of Python. For Python
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2.x, possible values are 0, 1, 2. For Python>=3.0, 3 is a valid value.
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For Python >= 3.4, 4 is a valid value. A negative value for the
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protocol parameter is equivalent to setting its value to
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HIGHEST_PROTOCOL.
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.. [1] https://docs.python.org/3/library/pickle.html
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.. versionadded:: 0.21.0
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See Also
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--------
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read_pickle : Load pickled pandas object (or any object) from file.
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DataFrame.to_hdf : Write DataFrame to an HDF5 file.
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DataFrame.to_sql : Write DataFrame to a SQL database.
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DataFrame.to_parquet : Write a DataFrame to the binary parquet format.
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Examples
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--------
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>>> original_df = pd.DataFrame({"foo": range(5), "bar": range(5, 10)})
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>>> original_df
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foo bar
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0 0 5
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1 1 6
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2 2 7
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3 3 8
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4 4 9
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>>> pd.to_pickle(original_df, "./dummy.pkl")
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>>> unpickled_df = pd.read_pickle("./dummy.pkl")
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>>> unpickled_df
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foo bar
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0 0 5
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1 1 6
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2 2 7
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3 3 8
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4 4 9
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>>> import os
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>>> os.remove("./dummy.pkl")
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"""
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path = _stringify_path(path)
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inferred_compression = _infer_compression(path, compression)
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f, fh = _get_handle(path, 'wb',
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compression=inferred_compression,
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is_text=False)
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if protocol < 0:
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protocol = pkl.HIGHEST_PROTOCOL
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try:
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f.write(pkl.dumps(obj, protocol=protocol))
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finally:
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for _f in fh:
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_f.close()
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def read_pickle(path, compression='infer'):
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"""
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Load pickled pandas object (or any object) from file.
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.. warning::
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Loading pickled data received from untrusted sources can be
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unsafe. See `here <https://docs.python.org/3/library/pickle.html>`__.
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Parameters
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----------
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path : str
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File path where the pickled object will be loaded.
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compression : {'infer', 'gzip', 'bz2', 'zip', 'xz', None}, default 'infer'
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For on-the-fly decompression of on-disk data. If 'infer', then use
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gzip, bz2, xz or zip if path ends in '.gz', '.bz2', '.xz',
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or '.zip' respectively, and no decompression otherwise.
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Set to None for no decompression.
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.. versionadded:: 0.20.0
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Returns
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-------
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unpickled : type of object stored in file
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See Also
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--------
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DataFrame.to_pickle : Pickle (serialize) DataFrame object to file.
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Series.to_pickle : Pickle (serialize) Series object to file.
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read_hdf : Read HDF5 file into a DataFrame.
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read_sql : Read SQL query or database table into a DataFrame.
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read_parquet : Load a parquet object, returning a DataFrame.
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Examples
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--------
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>>> original_df = pd.DataFrame({"foo": range(5), "bar": range(5, 10)})
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>>> original_df
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foo bar
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0 0 5
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1 1 6
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2 2 7
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3 3 8
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4 4 9
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>>> pd.to_pickle(original_df, "./dummy.pkl")
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>>> unpickled_df = pd.read_pickle("./dummy.pkl")
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>>> unpickled_df
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foo bar
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0 0 5
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1 1 6
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2 2 7
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3 3 8
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4 4 9
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>>> import os
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>>> os.remove("./dummy.pkl")
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"""
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path = _stringify_path(path)
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inferred_compression = _infer_compression(path, compression)
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def read_wrapper(func):
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# wrapper file handle open/close operation
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f, fh = _get_handle(path, 'rb',
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compression=inferred_compression,
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is_text=False)
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try:
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return func(f)
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finally:
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for _f in fh:
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_f.close()
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def try_read(path, encoding=None):
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# try with cPickle
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# try with current pickle, if we have a Type Error then
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# try with the compat pickle to handle subclass changes
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# pass encoding only if its not None as py2 doesn't handle
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# the param
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# cpickle
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# GH 6899
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try:
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with warnings.catch_warnings(record=True):
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# We want to silencce any warnings about, e.g. moved modules.
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return read_wrapper(lambda f: pkl.load(f))
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except Exception:
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# reg/patched pickle
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try:
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return read_wrapper(
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lambda f: pc.load(f, encoding=encoding, compat=False))
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# compat pickle
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except:
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return read_wrapper(
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lambda f: pc.load(f, encoding=encoding, compat=True))
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try:
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return try_read(path)
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except:
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if PY3:
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return try_read(path, encoding='latin1')
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raise
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# compat with sparse pickle / unpickle
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def _pickle_array(arr):
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arr = arr.view(np.ndarray)
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buf = BytesIO()
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write_array(buf, arr)
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return buf.getvalue()
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def _unpickle_array(bytes):
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arr = read_array(BytesIO(bytes))
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# All datetimes should be stored as M8[ns]. When unpickling with
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# numpy1.6, it will read these as M8[us]. So this ensures all
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# datetime64 types are read as MS[ns]
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if is_datetime64_dtype(arr):
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arr = arr.view(_NS_DTYPE)
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return arr
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