Add Commas to Number (Python)

addcommas.py

def add_commas(number):
    """Add commas to a number every 3 places and return the result as a string.
        Handles positives/negatives, cases where 0 < abs(x) < 1, and numbers
        passed as a string."""

    # Ensure that the argument is a string
    number = str(number)

    isnegative = number[0] == "-"

    # Remove negative signs (effectivly get absolute value) and split at any decimal point
    basenumber = number.replace("-","").split(".")

    newnumber = ""
    
    # If the case is 0 < abs(x) < 1
    if basenumber[0] == "0":
        newnumber = basenumber[0] + "." + basenumber[1]

        # Remove trailing 0s from the result
        while newnumber[-1:] == "0":
          newnumber = newnumber[:-1]
    
    elif basenumber[0] == "":
        newnumber = "0." + basenumber[1]

        # Remove trailing 0s from the result
        while newnumber[-1:] == "0":
          newnumber = newnumber[:-1]

    else:
        # For each digit going backwards, add it to the beginning of newnumber. If the modulo of i is 3 (every 3 digits), also add a comma
        i = 1
        while i <= len(basenumber[0]):
            newnumber = basenumber[0][-i] + newnumber

            if i % 3 == 0 and i != len(basenumber[0]):
              newnumber = "," + newnumber
            i += 1

        # Re-add decimal places
        if len(basenumber) > 1:
            newnumber += "." + basenumber[1]

            # Remove trailing 0s from the result
            while newnumber[-1:] == "0":
              newnumber = newnumber[:-1]

    # Remove leading 0s from the result unless it's before a decimal point
    while newnumber[0] == "0":
        if not newnumber[1] == ".":
            newnumber = newnumber[1:]
        else:
            break;

    # Remove leading commas from the result
    if newnumber[0] == ",":
        newnumber = newnumber[1:]

    # Re-add negative sign
    if isnegative:
        newnumber = "-" + newnumber
            
    return newnumber
  
if __name__ == "__main__":
    import sys
    
    if len(sys.argv) == 1:
        num = add_commas("-068204.1250")
    else:
        num = add_commas(sys.argv[1])
        
    print(num)