How can I convert an integer into a base-256 representation?

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I have some numbers that I want to interpret as RGB color tuples. The number represents the color like it were in base 256; i.e., the "65536s" digit represents the red component, the "256s" digit represents the green component, and the ones digit represents the blue component.

I wrote some complex code to do this, with a lot of special cases. Do I need my own code for this task? What is the simplest and most direct way to get this result?

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2 Answers

The integer type has this built-in:

>>> help(int.to_bytes)
Help on method_descriptor:

    to_bytes(self, /, length, byteorder, *, signed=False)
        Return an array of bytes representing an integer.
    
        length
          Length of bytes object to use.  An OverflowError is raised if the
          integer is not representable with the given number of bytes.
        byteorder
          The byte order used to represent the integer.  If byteorder is 'big',
          the most significant byte is at the beginning of the byte array.  If
          byteorder is 'little', the most significant byte is at the end of the
          byte array.  To request the native byte order of the host system, use
          `sys.byteorder' as the byte order value.
        signed
          Determines whether two's complement is used to represent the integer.
          If signed is False and a negative integer is given, an OverflowError
          is raised.

Your code produces an unsigned, big-endian result, of length 3, as a tuple of integer values. A bytes object is a sequence that gives you bytes when you iterate over it, so we can feed it directly to tuple to do the necessary conversion. Thus:

def convertBase256(n):
    return tuple(n.to_bytes(3, 'big'))

And we're done.

user_5236120 
def convertBase256(n):
 rgb=tuple((n >> Val) & 255 for Val in (16, 8, 0))
 return rgb
user_138092900
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