I have a list of integers:
var = [1, 5, 4, 17, 231, 89]
If I wanted to convert it to a list of bytes instead, I can do:
[(i).to_bytes(1, byteorder='big') for i in var]
Since each value in
var is less than 256, it can fit in one byte per integer. But if I had another list, say:
var = [1, 2, 15, 12]
This can fit an integer into half a byte, or more accurate to what I’m looking for, fit two integers per byte.
How can I specify to combine two integers into a byte if possible, both to and from?
Something like below:
var1 = [1, 5, 4, 17, 231, 89] var2 = [1, 2, 15, 12] def foo(var): if max(var) < 2**4: num_bytes = 0.5 elif max(var) < 2**8: num_bytes = 1 elif max(var) < 2**16: num_bytes = 2 if num_bytes >= 1: return [(i).to_bytes(num_bytes, byteorder='big') for i in var], num_bytes elif num_bytes = 0.5: # convert var to list of nybbles # combine two nybbles to a byte # create list of bytes (length is half length of var) # return it and num_bytes def unfoo(var, num_bytes): if num_bytes >= 1: print([int.from_bytes(i, 'big') for i in var]) elif num_bytes = 0.5: # print original list of integers again
I want to convert a list of integers into a list of bytes, but fitting two nybbles to a byte if it can fit, then do the conversion back.
Desired outcome is:
a, b = foo(var1) unfoo(a, b) # prints [1, 5, 4, 17, 231, 89] a, b = foo(var2) unfoo(a, b) # prints [1, 2, 15, 12]
I don’t want a list of smallest number of bits to represent a single number. Note the
max(list): if all values in the list can be 8-bits, fit it to 8-bits; if all values can be 16-bits, fit it to 16-bits; if all values can be a nybble, then make two nybble pairs into a list of bytes.
Basically if I have two integers that can fit in a nybble each, how do I concatenate both into a single byte? If I know that bytes need to be split into two, how can I do the split? I can always assume the original list will be divisible by 2.