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regardless of sign.
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.. function:: compress(string[, level])
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.. function:: compress(data[, level])
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Compresses the data in *string*, returning a string contained compressed data.
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Compresses the bytes in *data*, returning a bytes object containing compressed data.
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*level* is an integer from ``1`` to ``9`` controlling the level of compression;
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``1`` is fastest and produces the least compression, ``9`` is slowest and
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produces the most. The default value is ``6``. Raises the :exc:`error`
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regardless of sign.
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.. function:: decompress(string[, wbits[, bufsize]])
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.. function:: decompress(data[, wbits[, bufsize]])
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Decompresses the data in *string*, returning a string containing the
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Decompresses the bytes in *data*, returning a bytes object containing the
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uncompressed data. The *wbits* parameter controls the size of the window
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buffer, and is discussed further below.
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If *bufsize* is given, it is used as the initial size of the output
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Compression objects support the following methods:
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.. method:: Compress.compress(string)
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.. method:: Compress.compress(data)
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Compress *string*, returning a string containing compressed data for at least
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part of the data in *string*. This data should be concatenated to the output
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Compress *data*, returning a bytes object containing compressed data for at least
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part of the data in *data*. This data should be concatenated to the output
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produced by any preceding calls to the :meth:`compress` method. Some input may
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be kept in internal buffers for later processing.
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.. method:: Compress.flush([mode])
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All pending input is processed, and a string containing the remaining compressed
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All pending input is processed, and a bytes object containing the remaining compressed
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output is returned. *mode* can be selected from the constants
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:const:`Z_SYNC_FLUSH`, :const:`Z_FULL_FLUSH`, or :const:`Z_FINISH`,
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defaulting to :const:`Z_FINISH`. :const:`Z_SYNC_FLUSH` and
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:const:`Z_FULL_FLUSH` allow compressing further strings of data, while
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:const:`Z_FULL_FLUSH` allow compressing further bytestrings of data, while
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:const:`Z_FINISH` finishes the compressed stream and prevents compressing any
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more data. After calling :meth:`flush` with *mode* set to :const:`Z_FINISH`,
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the :meth:`compress` method cannot be called again; the only realistic action is
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.. attribute:: Decompress.unused_data
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A string which contains any bytes past the end of the compressed data. That is,
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A bytes object which contains any bytes past the end of the compressed data. That is,
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this remains ``""`` until the last byte that contains compression data is
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available. If the whole string turned out to contain compressed data, this is
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``""``, the empty string.
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available. If the whole bytestring turned out to contain compressed data, this is
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``b""``, an empty bytes object.
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The only way to determine where a string of compressed data ends is by actually
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The only way to determine where a bytestring of compressed data ends is by actually
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decompressing it. This means that when compressed data is contained part of a
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larger file, you can only find the end of it by reading data and feeding it
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followed by some non-empty string into a decompression object's
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followed by some non-empty bytestring into a decompression object's
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:meth:`decompress` method until the :attr:`unused_data` attribute is no longer
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.. attribute:: Decompress.unconsumed_tail
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A string that contains any data that was not consumed by the last
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A bytes object that contains any data that was not consumed by the last
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:meth:`decompress` call because it exceeded the limit for the uncompressed data
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buffer. This data has not yet been seen by the zlib machinery, so you must feed
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it (possibly with further data concatenated to it) back to a subsequent
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:meth:`decompress` method call in order to get correct output.
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.. method:: Decompress.decompress(string[, max_length])
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.. method:: Decompress.decompress(data[, max_length])
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Decompress *string*, returning a string containing the uncompressed data
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Decompress *data*, returning a bytes object containing the uncompressed data
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corresponding to at least part of the data in *string*. This data should be
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concatenated to the output produced by any preceding calls to the
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:meth:`decompress` method. Some of the input data may be preserved in internal
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If the optional parameter *max_length* is supplied then the return value will be
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no longer than *max_length*. This may mean that not all of the compressed input
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can be processed; and unconsumed data will be stored in the attribute
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:attr:`unconsumed_tail`. This string must be passed to a subsequent call to
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:attr:`unconsumed_tail`. This bytestring must be passed to a subsequent call to
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:meth:`decompress` if decompression is to continue. If *max_length* is not
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supplied then the whole input is decompressed, and :attr:`unconsumed_tail` is an
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supplied then the whole input is decompressed, and :attr:`unconsumed_tail` is
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.. method:: Decompress.flush([length])
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All pending input is processed, and a string containing the remaining
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All pending input is processed, and a bytes object containing the remaining
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uncompressed output is returned. After calling :meth:`flush`, the
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:meth:`decompress` method cannot be called again; the only realistic action is
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to delete the object.
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Doc/library/zlib.rst
