character encoding - Python convert strings of bytes to byte array

Question

For example given an arbitrary string. Could be chars or just random bytes:

string = 'xf0x9fxa4xb1'

I want to output:

b'xf0x9fxa4xb1'

This seems so simple, but I could not find an answer anywhere. Of course just typing the b followed by the string will do. But I want to do this runtime, or from a variable containing the strings of byte.

if the given string was AAAA or some known characters I can simply do string.encode('utf-8'), but I am expecting the string of bytes to just be random. Doing that to 'xf0x9fxa4xb1' ( random bytes ) produces unexpected result b'xc3xb0xc2x9fxc2xa4xc2xb1'.

There must be a simpler way to do this?

Edit:

I want to convert the string to bytes without using an encoding

Answer 1

The Latin-1 character encoding trivially (and unlike every other encoding supported by Python) encodes every code point in the range 0x00-0xff to a byte with the same value.

byteobj = 'xf0x9fxa4xb1'.encode('latin-1')

You say you don't want to use an encoding, but the alternatives which avoid it seem far inferior.

The UTF-8 encoding is unsuitable because, as you already discovered, code points above 0x7f map to a sequence of multiple bytes (up to four bytes) none of which are exactly the input code point as a byte value.

Omitting the argument to .encode() (as in a now-deleted answer) forces Python to guess an encoding, which produces system-dependent behavior (probably picks UTF-8 on most systems except Windows, where it will typically instead choose something much more unpredictable, as well as usually much more sinister and horrible).