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I have an unsigned integer that is 16 bits coming in on the USB, these appear as 2 bytes in my list that is returned, e.g. [0x20, 0x00]. How would I combine these in to a number in python?

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    Depends. Is the expected result 8192 or 32? Commented Jan 31, 2014 at 9:57
  • @Carsten 32 is the expected result. Commented Jan 31, 2014 at 9:59
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    Answer below changed accordingly Commented Jan 31, 2014 at 9:59
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    is it really [0x20, 0x00] or ["0x20", "0x00"] Commented Jan 31, 2014 at 10:00
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    No there hexadecimal numbers in my list not strings. Commented Jan 31, 2014 at 10:06

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If your input is [0x20, 0x00], then you can do (arr[1]<<8)|arr[0].

If your input is ["0x20", "0x00"], then you can do int(arr[1],16)<<8)|int(arr[0],16).

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This also works:

>>> import struct
>>> struct.unpack('<H', ''.join(map(chr, [0x20, 0x00])))[0]
32

The struct module is quite generic, it can be used in similar situations, and it becomes convenient as soon as 4-byte or 8-byte integers are needed.

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