How to remove '\x' from a hex string in Python?

Question

I'm reading a wav audio file in Python using wave module. The readframe() function in this library returns frames as hex string. I want to remove \x of this string, but translate() function doesn't work as I want:

>>> input = wave.open(r"G:\Workspace\wav\1.wav",'r')
>>> input.readframes (1)
'\xff\x1f\x00\xe8'
>>> '\xff\x1f\x00\xe8'.translate(None,'\\x')
'\xff\x1f\x00\xe8'
>>> '\xff\x1f\x00\xe8'.translate(None,'\x')
ValueError: invalid \x escape
>>> '\xff\x1f\x00\xe8'.translate(None,r'\x')
'\xff\x1f\x00\xe8'
>>> 

Any way I want divide the result values by 2 and then add \x again and generate a new wav file containing these new values. Does any one have any better idea?

What's wrong?

Solution 1

Indeed, you don't have backslashes in your string. So, that's why you can't remove them.

If you try to play with each hex character from this string (using ord() and len() functions - you'll see their real values. Besides, the length of your string is just 4, not 16.

You can play with several solutions to achieve your result: 'hex' encode:

'\xff\x1f\x00\xe8'.encode('hex')
'ff1f00e8'

Or use repr() function:

repr('\xff\x1f\x00\xe8').translate(None,r'\\x')

Solution 2

One way to do what you want is:

>>> s = '\xff\x1f\x00\xe8'
>>> ''.join('%02x' % ord(c) for c in s)
'ff1f00e8'

---

The reason why translate is not working is that what you are seeing is not the string itself, but its representation. In other words, \x is not contained in the string:

>>> '\\x' in '\xff\x1f\x00\xe8'
False

\xff, \x1f, \x00 and \xe8 are the hexadecimal representation of for characters (in fact, len(s) == 4, not 24).

Solution 3

Use the encode method:

>>> s = '\xff\x1f\x00\xe8'
>>> print s.encode("hex")
'ff1f00e8'

Comments

[Ebrahim Ghasemi]

Does it have any reverse way to? I mean how can I convert 'ff1f00e8' to '\xff\x1f\x00\xe8' again? any Decode function?

[Dmitry]

Reverse: 'ff1f00e8'.decode('hex') :) What about length - was playing with backslashes in the initial string.