Python in a Nutshell, 2nd Edition

Compressed Files

Storage space and transmission bandwidth are increasingly cheap and abundant, but in many cases you can save such resources, at the expense of some computational effort, by using compression. Computational power grows cheaper and more abundant even faster than other resources, such as bandwidth, so compression’s popularity keeps growing. Python makes it easy for your programs to support compression, since the Python standard library contains several modules dedicated to compression.

Since Python offers so many ways to deal with compression, some guidance may be helpful. Files containing data compressed with the zlib module are not automatically interchangeable with other programs, except for those files built with the zipfile module, which respects the standard format of ZIP file archives. You can write custom programs, with any language able to use InfoZip’s free zlib compression library, to read files produced by Python programs using the zlib module. However, if you do need to interchange compressed data with programs coded in other languages, but have a choice of compression methods, I suggest you use modules bzip2 (best), gzip, or zipfile instead. Module zlib, however, may be useful when you want to compress some parts of datafiles that are in some proprietary format of your own and need not be interchanged with any other program except those that make up your own application.

The gzip Module

The gzip module lets you read and write files compatible with those ...