Converting bytearray to short int in python

Question

I have a long bytearray

barray=b'\x00\xfe\x4b\x00...

What would be the best way to convert it to a list of 2-byte integers?

Answer 1

You can use the struct package for that:

from struct import unpack

tuple_of_shorts = unpack('h'*(len(barray)//2),barray)

This will produce signed shorts. For unsigned ones, use 'H' instead:

tuple_of_shorts = unpack('H'*(len(barray)//2),barray)

This produces on a little-endian machine for your sample input:

>>> struct.unpack('h'*(len(barray)//2),barray)
(-512, 75)
>>> struct.unpack('H'*(len(barray)//2),barray)
(65024, 75)

In case you want to work with big endian, or little endian, you can put a > (big endian) or < (little endian) in the specifications. For instance:

# Big endian
tuple_of_shorts = unpack('>'+'H'*(len(barray)//2),barray)  # unsigned
tuple_of_shorts = unpack('>'+'h'*(len(barray)//2),barray)  # signed

# Little endian
tuple_of_shorts = unpack('<'+'H'*(len(barray)//2),barray)  # unsigned
tuple_of_shorts = unpack('<'+'h'*(len(barray)//2),barray)  # signed

Generating:

>>> unpack('>'+'H'*(len(barray)//2),barray)  # big endian, unsigned
(254, 19200)
>>> unpack('>'+'h'*(len(barray)//2),barray)  # big endian, signed
(254, 19200)
>>> unpack('<'+'H'*(len(barray)//2),barray)  # little endian, unsigned
(65024, 75)
>>> unpack('<'+'h'*(len(barray)//2),barray)  # little endian, signed
(-512, 75)