Keep Fractions As Factors

There's many cases where I want symbols within the numerator and denominator of a fraction to be strictly grouped within that fraction. For instance, I might want this: 16 1 --*-

Solution 1:

Thanks to this answer, I found that using UnevaluatedExpr gives me what I want. This modified snippet:

from sympy import Mul, pretty
from sympy import UnevaluatedExpr
from sympy.abc import a, b

left = UnevaluatedExpr(16) / 37
center = 1 / (4*a*b)
right = a + b
expr = Mul(left, center, right, evaluate=False)

print(pretty(expr))

gives:

16   1          
--*-----*(a + b)
37 4*a*b

However, this feels really hacky. Everything in the sympy docs seem to indicate that using Rational is the correct way to create a fraction from numeric literals.