Python - mechanism to identify compressed file type and uncompress

Question

A compressed file can be classified into below logical groups
a. The operating system which you are working on (*ix, Win) etc.
b. Different types of compression algo

Answer 1

The accepted solution looks great, but it doesn't work with python-3, here are the modifications that made it work -- using binary I/O instead of strings:

magic_dict = {
    b"\x1f\x8b\x08": "gz",
    b"\x42\x5a\x68": "bz2",
    b"\x50\x4b\x03\x04": "zip"
    }
''' SKIP '''
    with open(filename, "rb") as f:
''' The rest is the same '''