all Python 3zlibterm

zlib

module

Compresses and decompresses data with the gzip-compatible DEFLATE algorithm, plus crc32 and adler32 checksums.

Syntax

import zlib

zlib works on bytes in memory: compressing a response, storing data compactly, computing a checksum. For .gz files use gzip — it adds a header that zlib.decompress() does not understand by default; for multi-file archives use zipfile. Only bytes can be compressed: encode a string first, for example with s.encode(), or you get TypeError.

Examples

import zlib
data = b"abc" * 1000
packed = zlib.compress(data)
print(len(data), len(packed) < 50)  # → 3000 True
print(zlib.decompress(packed) == data)  # → True
print(zlib.crc32(b"hello"))  # → 907060870

See also

Common errors

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