convert a binary file in a list (python)

You need to understand that "\x21" and "!" are two ways of representing the same thing

so "\x21\x23\x22\x21\x22\x31" is the same as '!#"!"1'

>>> "\x21\x23\x22\x21\x22\x31"  == '!#"!"1'
True

>>> infile = open('infile.txt', 'rb')
>>> list(infile.read())
['!', '#', '"', '!', '"', '1']
>>> ['!', '#', '"', '!', '"', '1'] == ["\x21","\x23","\x22","\x21","\x22","\x31"]
True

So you see they are the same thing, but python always tries to pick the most user friendly way to display the characters

You can read the binary data into a string just like you would do with text data, just make sure to open the file in binary mode (the b flag in the call to open()):

with open('file.bin', 'rb') as f:
   data = f.read()

data now contains the characters from the file as a string, like "\x21\x23\x22\x21\x22\x31".

Assume that myfile.txt has 'abcdef\n' in it...

>>> fh = open('myfile.txt', 'rb')
>>> list(fh.read())
['a', 'b', 'c', 'd', 'e', 'f', '\n']

To make "a kind of array" of characters, an extremely efficient way (more than using a list!) is to use Python's standard library array module:

res = array.array('c')
with open('binaryfile', 'rb') as f:
    while True:
        try: res.fromfile(f, 1024 * 1024)
        except EOFError: break

This reads no more than a megabyte at a time (that's the 1024 * 1024), but keeps going until the file's all done -- you can tweak that behavior as you prefer, of course.