Original code copyright (C) 2009-2022 Rudolf Cardinal (

This file is part of cardinal_pythonlib.

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Compression functions.

cardinal_pythonlib.compression.gunzip_string(zipped: bytes, encoding: str = 'utf-8') str[source]

Reverses gzip_string(), i.e. un-gzip-compresses it, then decodes it into a string.

  • zipped – zipped data

  • encoding – encoding that was used for the string prior to compression



Return type:


:raises - OsError if the data wasn’t gzipped: :raises - UnicodeDecodeError if the decompressed data won’t decode:

cardinal_pythonlib.compression.gzip_string(text: str, encoding: str = 'utf-8') bytes[source]

Encodes a string, then compresses it with gzip.

When you send data over HTTP and wish to compress it, what should you do?

  • text – a string to compress

  • encoding – encoding to use when converting string to bytes prior to compression


gzip-compressed data

Return type:


Test code:

import io
import gzip

teststring = "Testing; one, two, three."
testbytes = teststring.encode("utf-8")

gz1 = gzip.compress(testbytes)

out1 = io.BytesIO()
with gzip.GzipFile(fileobj=out1, mode="w") as gzfile1:
gz2 = out1.getvalue()

print(len(gz1) == len(gz2))  # False
print(gz1 == gz2)  # False
# ... but the difference is probably in the timestamp bytes!