Turn floats to integers in sympy

Question

Is there a fast way to turn floats that are actually integers, to integers in python? For example: 2.0*x+3.1 , I would like to appear as 2*x+3.1 . I could loop through the numbers in the expression and check one by one if x = int(x) and then replace them (or something like that), but I was wondering if there is a faster, built-in method to do so.

Thank you!

Answer 1

There are a few ways to do this. You could nsimplify(expr, rational=True) but that will change the 3.1 to 31/10 and then you would have to undo that. The use of replace does not replace thing which are tested as equal. So the only one-pass solution that I know of is a custom function:

>>> def intify(expr):
...  floats = S(expr).atoms(Float)
...  ints = [i for i in floats if int(i) == i]
...  return expr.xreplace(dict(zip(ints, [int(i) for i in ints])))
...
>>> intify(2.0*x+3.1)
2*x + 3.1