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.. class:: BZ2File(filename[, mode[, buffering[, compresslevel]]])
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Open a bz2 file. Mode can be either ``'r'`` or ``'w'``, for reading (default)
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Open a bz2 file. Mode can be either ``'r'`` or ``'w'``, for reading (default)
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or writing. When opened for writing, the file will be created if it doesn't
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exist, and truncated otherwise. If *buffering* is given, ``0`` means unbuffered,
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and larger numbers specify the buffer size; the default is ``0``. If
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*compresslevel* is given, it must be a number between ``1`` and ``9``; the
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default is ``9``. Add a ``'U'`` to mode to open the file for input with
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universal newline support. Any line ending in the input file will be seen as a
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``'\n'`` in Python. Also, a file so opened gains the attribute
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exist, and truncated otherwise. If *buffering* is given, ``0`` means
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unbuffered, and larger numbers specify the buffer size; the default is
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``0``. If *compresslevel* is given, it must be a number between ``1`` and
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``9``; the default is ``9``. Add a ``'U'`` to mode to open the file for input
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with universal newline support. Any line ending in the input file will be
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seen as a ``'\n'`` in Python. Also, a file so opened gains the attribute
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:attr:`newlines`; the value for this attribute is one of ``None`` (no newline
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read yet), ``'\r'``, ``'\n'``, ``'\r\n'`` or a tuple containing all the newline
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types seen. Universal newlines are available only when reading. Instances
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support iteration in the same way as normal :class:`file` instances.
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.. method:: BZ2File.close()
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Close the file. Sets data attribute :attr:`closed` to true. A closed file cannot
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be used for further I/O operations. :meth:`close` may be called more than once
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.. method:: BZ2File.read([size])
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Read at most *size* uncompressed bytes, returned as a string. If the *size*
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argument is negative or omitted, read until EOF is reached.
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.. method:: BZ2File.readline([size])
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Return the next line from the file, as a string, retaining newline. A
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non-negative *size* argument limits the maximum number of bytes to return (an
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incomplete line may be returned then). Return an empty string at EOF.
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.. method:: BZ2File.readlines([size])
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Return a list of lines read. The optional *size* argument, if given, is an
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approximate bound on the total number of bytes in the lines returned.
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.. method:: BZ2File.xreadlines()
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For backward compatibility. :class:`BZ2File` objects now include the performance
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optimizations previously implemented in the :mod:`xreadlines` module.
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This exists only for compatibility with the method by this name on :class:`file`
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objects, which is deprecated. Use ``for line in file`` instead.
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.. method:: BZ2File.seek(offset[, whence])
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Move to new file position. Argument *offset* is a byte count. Optional argument
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*whence* defaults to ``os.SEEK_SET`` or ``0`` (offset from start of file; offset
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should be ``>= 0``); other values are ``os.SEEK_CUR`` or ``1`` (move relative to
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current position; offset can be positive or negative), and ``os.SEEK_END`` or
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``2`` (move relative to end of file; offset is usually negative, although many
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platforms allow seeking beyond the end of a file).
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Note that seeking of bz2 files is emulated, and depending on the parameters the
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operation may be extremely slow.
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.. method:: BZ2File.tell()
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Return the current file position, an integer (may be a long integer).
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.. method:: BZ2File.write(data)
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Write string *data* to file. Note that due to buffering, :meth:`close` may be
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needed before the file on disk reflects the data written.
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.. method:: BZ2File.writelines(sequence_of_strings)
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Write the sequence of strings to the file. Note that newlines are not added. The
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sequence can be any iterable object producing strings. This is equivalent to
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calling write() for each string.
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read yet), ``'\r'``, ``'\n'``, ``'\r\n'`` or a tuple containing all the
59
newline types seen. Universal newlines are available only when
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reading. Instances support iteration in the same way as normal :class:`file`
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Close the file. Sets data attribute :attr:`closed` to true. A closed file
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cannot be used for further I/O operations. :meth:`close` may be called
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more than once without error.
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.. method:: read([size])
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Read at most *size* uncompressed bytes, returned as a string. If the
74
*size* argument is negative or omitted, read until EOF is reached.
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.. method:: readline([size])
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Return the next line from the file, as a string, retaining newline. A
80
non-negative *size* argument limits the maximum number of bytes to return
81
(an incomplete line may be returned then). Return an empty string at EOF.
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.. method:: readlines([size])
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Return a list of lines read. The optional *size* argument, if given, is an
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approximate bound on the total number of bytes in the lines returned.
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.. method:: xreadlines()
92
For backward compatibility. :class:`BZ2File` objects now include the
93
performance optimizations previously implemented in the :mod:`xreadlines`
97
This exists only for compatibility with the method by this name on
98
:class:`file` objects, which is deprecated. Use ``for line in file``
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.. method:: seek(offset[, whence])
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Move to new file position. Argument *offset* is a byte count. Optional
105
argument *whence* defaults to ``os.SEEK_SET`` or ``0`` (offset from start
106
of file; offset should be ``>= 0``); other values are ``os.SEEK_CUR`` or
107
``1`` (move relative to current position; offset can be positive or
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negative), and ``os.SEEK_END`` or ``2`` (move relative to end of file;
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offset is usually negative, although many platforms allow seeking beyond
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Note that seeking of bz2 files is emulated, and depending on the
113
parameters the operation may be extremely slow.
118
Return the current file position, an integer (may be a long integer).
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.. method:: write(data)
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Write string *data* to file. Note that due to buffering, :meth:`close` may
124
be needed before the file on disk reflects the data written.
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.. method:: writelines(sequence_of_strings)
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Write the sequence of strings to the file. Note that newlines are not
130
added. The sequence can be any iterable object producing strings. This is
131
equivalent to calling write() for each string.
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Sequential (de)compression
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.. class:: BZ2Compressor([compresslevel])
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Create a new compressor object. This object may be used to compress data
140
sequentially. If you want to compress data in one shot, use the :func:`compress`
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function instead. The *compresslevel* parameter, if given, must be a number
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between ``1`` and ``9``; the default is ``9``.
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.. method:: BZ2Compressor.compress(data)
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Provide more data to the compressor object. It will return chunks of compressed
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data whenever possible. When you've finished providing data to compress, call
149
the :meth:`flush` method to finish the compression process, and return what is
150
left in internal buffers.
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.. method:: BZ2Compressor.flush()
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Finish the compression process and return what is left in internal buffers. You
156
must not use the compressor object after calling this method.
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sequentially. If you want to compress data in one shot, use the
145
:func:`compress` function instead. The *compresslevel* parameter, if given,
146
must be a number between ``1`` and ``9``; the default is ``9``.
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.. method:: compress(data)
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Provide more data to the compressor object. It will return chunks of
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compressed data whenever possible. When you've finished providing data to
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compress, call the :meth:`flush` method to finish the compression process,
154
and return what is left in internal buffers.
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Finish the compression process and return what is left in internal
160
buffers. You must not use the compressor object after calling this method.
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.. class:: BZ2Decompressor()