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zlib

The functions in this module allow compression and decompression using the
zlib library, which is based on GNU zip.

adler32(string[, start]) -- Compute an Adler-32 checksum.
compress(data[, level]) -- Compress data, with compression level 0-9 or -1.
compressobj([level[, ...]]) -- Return a compressor object.
crc32(string[, start]) -- Compute a CRC-32 checksum.
decompress(string,[wbits],[bufsize]) -- Decompresses a compressed string.
decompressobj([wbits[, zdict]]) -- Return a decompressor object.

'wbits' is window buffer size and container format.
Compressor objects support compress() and flush() methods; decompressor
objects support decompress() and flush().

Classes

error

with_traceback(...)

  Exception.with_traceback(tb) --
      set self.__traceback__ to tb and return self.

args = <attribute 'args' of 'BaseException' objects>

Functions

adler32

adler32(data, value=1, /)

  Compute an Adler-32 checksum of data.

    value
      Starting value of the checksum.

  The returned checksum is an integer.

compress

compress(data, /, level=-1)

  Returns a bytes object containing compressed data.

    data
      Binary data to be compressed.
    level
      Compression level, in 0-9 or -1.

compressobj

compressobj(level=-1, method=8, wbits=15, memLevel=8, strategy=0, zdict=None)

  Return a compressor object.

    level
      The compression level (an integer in the range 0-9 or -1; default is
      currently equivalent to 6).  Higher compression levels are slower,
      but produce smaller results.
    method
      The compression algorithm.  If given, this must be DEFLATED.
    wbits
      +9 to +15: The base-two logarithm of the window size.  Include a zlib
          container.
      -9 to -15: Generate a raw stream.
      +25 to +31: Include a gzip container.
    memLevel
      Controls the amount of memory used for internal compression state.
      Valid values range from 1 to 9.  Higher values result in higher memory
      usage, faster compression, and smaller output.
    strategy
      Used to tune the compression algorithm.  Possible values are
      Z_DEFAULT_STRATEGY, Z_FILTERED, and Z_HUFFMAN_ONLY.
    zdict
      The predefined compression dictionary - a sequence of bytes
      containing subsequences that are likely to occur in the input data.

crc32

crc32(data, value=0, /)

  Compute a CRC-32 checksum of data.

    value
      Starting value of the checksum.

  The returned checksum is an integer.

decompress

decompress(data, /, wbits=15, bufsize=16384)

  Returns a bytes object containing the uncompressed data.

    data
      Compressed data.
    wbits
      The window buffer size and container format.
    bufsize
      The initial output buffer size.

decompressobj

decompressobj(wbits=15, zdict=b'')

  Return a decompressor object.

    wbits
      The window buffer size and container format.
    zdict
      The predefined compression dictionary.  This must be the same
      dictionary as used by the compressor that produced the input data.

Other members

DEFLATED = 8

DEF_BUF_SIZE = 16384

DEF_MEM_LEVEL = 8

MAX_WBITS = 15

ZLIB_RUNTIME_VERSION = '1.2.13'

ZLIB_VERSION = '1.2.13'

Z_BEST_COMPRESSION = 9

Z_BEST_SPEED = 1

Z_BLOCK = 5

Z_DEFAULT_COMPRESSION = -1

Z_DEFAULT_STRATEGY = 0

Z_FILTERED = 1

Z_FINISH = 4

Z_FIXED = 4

Z_FULL_FLUSH = 3

Z_HUFFMAN_ONLY = 2

Z_NO_COMPRESSION = 0

Z_NO_FLUSH = 0

Z_PARTIAL_FLUSH = 1

Z_RLE = 3

Z_SYNC_FLUSH = 2

Z_TREES = 6