Encoding ASCII text as DNA (quaternary base)

encode_ascii_as_dna.py

def to_base(n, bse):
    digs = "0123456789abcdefghijklmnopqrstuvwxyz"
    tmp = []
    while n:
        n, i = divmod(n, bse)
        tmp.append(digs[i])
    return "".join(tmp[::-1])

def chng_frm_base(s, frm_bse, to_bse):
    if to_bse < 2 or to_bse > 36 or frm_bse < 2 or frm_bse > 36:
        raise ValueError("bases must be between 2-36")
    try:
        return to_base(int(s, frm_bse), to_bse)
    except ValueError:
        try:
            n = int("".join([ch for ch in s if ch.isdigit()]), frm_bse)
            return to_base(n, to_bse)
        except ValueError:
            return 0
    
def to_dna_bases(str):
  bin_ascii = bin(int.from_bytes(str.encode(), 'big'))[2:]
  new_base = chng_frm_base(bin_ascii, 2, 4)
  char_replaced = new_base.replace("0", "A")
  char_replaced = char_replaced.replace("1", "T")
  char_replaced = char_replaced.replace("2", "G")
  char_replaced = char_replaced.replace("3", "C")
  return char_replaced
  
def from_dna_bases(string):
  char_replaced = string.replace("A", "0")
  char_replaced = char_replaced.replace("T", "1")
  char_replaced = char_replaced.replace("G", "2")
  char_replaced = char_replaced.replace("C", "3")
  bin_ascii = chng_frm_base(char_replaced, 4, 2)
  n = int(bin_ascii, 2)
  final = n.to_bytes((n.bit_length() + 7) // 8, 'big').decode()
  return final


dna_string = to_dna_bases("hello, world")
real_string = from_dna_bases(dna_string)
print(dna_string + " means `" + real_string + "`")