Convert decimal to a mathematical multiple fractions of 1/4 in Python

Question

I want to compute a cup size based on a weight. One cup is defined as 240gr weight. I need to get the number of cups of a weight x in gr (decimal number), in the mathematical multiple fraction of 1/4. Result should be a string.

So, possible values should be limited to: 0, 1/4, 1/2, 3/4, 1, 1 1/4, 1 1/2, 1 3/4, 2 and so on.

Examples:

x = 130.3

cup_size: 1/2

x = 10

cup_size: 0

x = 310

cup_size: 1 1/4

How can I implement this in python? I was reading the Fractions module but I can't find something as I need.

As requested by Nathaniel, I'm not sure how to solve this math thing in python. I think it could exists a method in a library to do that. That's why I'm asking here.

So far, what I've tried is to convert with as_integer_ratio method:

weight = 351
unit = 240
weight_to_convert = int(round(weight/unit))
print(weight_to_convert.as_integer_ratio())

But this is not working, is just giving me the value as the nearest integer fraction.

Answer 1

The following might nudge you in the right direction:

def cups(val):
    full, quarter = divmod(val // 60, 4)
    if not (full or quarter):
        return "0"
    f = f"{full:.0f}" if full else ""
    if quarter:
        if quarter == 2:
            f += " 1/2"
        else:
            f += f" {quarter:.0f}/4" 
    return f.strip()

>>> cups(130)
'1/2'
>>> cups(310)
'1 1/4'
>>> cups(10)
'0'

Some docs:

• divmod
• f-strings