Open a bzip2-compressed file in binary mode.
If filename is a str or bytes object, open the named file
directly. Otherwise, filename should be a file object, which will
be used to read or write the compressed data.
The mode argument can be either 'r' for reading (default), 'w' for
overwriting, 'x' for exclusive creation, or 'a' for appending. These
can equivalently be given as 'rb', 'wb', 'xb' and 'ab'
respectively.
If filename is a file object (rather than an actual file name), a mode of
'w' does not truncate the file, and is instead equivalent to 'a'.
The buffering argument is ignored. Its use is deprecated.
If mode is 'w' or 'a', compresslevel can be a number between
1 and 9 specifying the level of compression: 1 produces the
least compression, and 9 (default) produces the most compression.
If mode is 'r', the input file may be the concatenation of multiple
compressed streams.
BZ2File provides all of the members specified by the
io.BufferedIOBase, except for detach() and truncate().
Iteration and the with statement are supported.
BZ2File also provides the following method:
-
peek([n])
Return buffered data without advancing the file position. At least one
byte of data will be returned (unless at EOF). The exact number of bytes
returned is unspecified.
Note
While calling peek() does not change the file position of
the BZ2File, it may change the position of the underlying file
object (e.g. if the BZ2File was constructed by passing a file
object for filename).
Changed in version 3.1: Support for the with statement was added.
Changed in version 3.3: The fileno(), readable(), seekable(), writable(),
read1() and readinto() methods were added.
Changed in version 3.3: Support was added for filename being a file object instead of an
actual filename.
Changed in version 3.3: The 'a' (append) mode was added, along with support for reading
multi-stream files.
Changed in version 3.4: The 'x' (exclusive creation) mode was added.
Changed in version 3.5: The read() method now accepts an argument of
None.