The default wbits valueĬorresponds to the largest window size and requires a zlib header andīufsize is the initial size of the buffer used to hold decompressed data. Than the size originally used to compress the stream using a too-small When decompressing a stream, the window size must not be smaller The window size logarithm, and automatically accepts either +40 to +47 = 32 + (8 to 15): Uses the low 4 bits of the value as +24 to +31 = 16 + (8 to 15): Uses the low 4 bits of the value as The input must be a raw stream with no header or trailer. −8 to −15: Uses the absolute value of wbits as the window size The inputĠ: Automatically determine the window size from the zlib header. +8 to +15: The base-two logarithm of the window size. It is similar to the parameter for compressobj(), but accepts (or “window size”), and what header and trailer format is expected. The wbits parameter controls the size of the history buffer Raises the error exception if any error occurs. If bufsize is given, it is used as the initial size of the outputīuffer. The format of data, and is discussed further below. decompress ( data, /, wbits = MAX_WBITS, bufsize = DEF_BUF_SIZE ) ¶ĭecompresses the bytes in data, returning a bytes object containing the To generate the same numeric value when using Python 2 or earlier, That are expected to be most common should come at the end of the dictionary.Ĭhanged in version 3.0: The result is always unsigned. To occur frequently in the data that is to be compressed. (such as a bytes object) containing subsequences that are expected Zdict is a predefined compression dictionary. Z_DEFAULT_STRATEGY, Z_FILTERED, Z_HUFFMAN_ONLY, Strategy is used to tune the compression algorithm. Higher values use more memory, but are faster and produce smaller output. The memLevel argument controls the amount of memory used for the Window size logarithm, while including a basic gzip header +25 to +31 = 16 + (9 to 15): Uses the low 4 bits of the value as the Window size logarithm, while producing a raw output stream with no −9 to −15: Uses the absolute value of wbits as the Resulting output will include a zlib-specific header and trailer. Larger values produceīetter compression at the expense of greater memory usage. +9 to +15: The base-two logarithm of the window size, which “window size”) used when compressing data, and whether a header and The wbits argument controls the size of the history buffer (or the Z_DEFAULT_COMPRESSION represents a default compromise between speed and compression The default value is -1 (Z_DEFAULT_COMPRESSION). While a value of 9 (Z_BEST_COMPRESSION) is slowest and produces the most.Ġ (Z_NO_COMPRESSION) is no compression. Level is the compression level – an integer from 0 to 9 or -1.Ī value of 1 (Z_BEST_SPEED) is fastest and produces the least compression, Returns a compression object, to be used for compressing data streams that won’t compressobj ( level=-1, method=DEFLATED, wbits=MAX_WBITS, memLevel=DEF_MEM_LEVEL, strategy=Z_DEFAULT_STRATEGY ) ¶ The algorithm is designed for use as a checksum algorithm, it is not suitableĬhanged in version 3.6: level can now be used as a keyword parameter. Strong, and should not be used for authentication or digital signatures. Passing in value allows computing a running checksum over theĬoncatenation of several inputs. The starting value of the checksum otherwise, a default value of 1
Reliable as a CRC32 but can be computed much more quickly.) The result adler32 ( data ) ¶Ĭomputes an Adler-32 checksum of data. error ¶Įxception raised on compression and decompression errors. The available exception and functions in this module are: exception zlib.
STICKY NOTES FOR DESKTOP WINDOWS MANUAL
This documentation doesn’t attempt to cover all of the permutations Ĭonsult the zlib manual at for authoritativeįor reading and writing.
Zlib’s functions have many options and often need to be used in a particular Incompatibilities between the Python module and versions of the zlib libraryĮarlier than 1.1.3 1.1.3 has a security vulnerability, so we recommend using Zlib - Compression compatible with gzip ¶įor applications that require data compression, the functions in this moduleĪllow compression and decompression, using the zlib library.
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