How to round away from 0 in Python 3.x?

Question

In Python 2 rounding is done away from 0, so, for example, round(0.5) is 1.0.
In Python 3.x, however, rounding is done toward the even choice, so round(0.5) is 0.
What function can I use in Python 3.x to get the old behavior?

Answer 1

If your code is not particularly performance sensitive, you can use the standard decimal library to achieve the result you want. Decimal().quantize() allows choosing the rounding method:

from decimal import Decimal, ROUND_HALF_UP
result = float(Decimal(0.5).quantize(Decimal(0), rounding=ROUND_HALF_UP))
print(result)  # Will output 1.0

Answer 2

Equivalent of Python 2.7 round() when rounding to an integer (one-parameter):

import math
def py2round(x):
    if x >= 0.0:
        return math.floor(x + 0.5)
    else:
        return math.ceil(x - 0.5)