Implement Python 3's round function in Python 2.7

Question

I am using some old codes written in Python 3 in my Google-App-Engine project which is using Python 2.7. The different round() algorithms in Python 3 and Python 2 gives me a headache. Is there any convenient way to implement a Python 3's round() method in Python 2.7?

A further question: Python 2 and Python 3 handle the integer operations quite differently. For example the following statements have different outputs in Python 2 and 3:

2/4   # 0 in Python 2, 0.5 in Python 3
round(3/2)  
math.ceil(0.5)   # 1.0 in Python 2, 1 in Python 3

Any easy way to convert codes from Python 3 to Python 2 while keeping the behavior to be exactly the same?

Thanks!

Use `from __future__ import division` to get py3.x's division behaviour in py2.x. — Ashwini Chaudhary, Aug 08 '13 at 00:50

score 4 · Accepted Answer · answered Aug 08 '13 at 00:49

4

Banker's rounding is implemented in future. Float division can be made the default with a __future__ import.

from __future__ import division
from future.modified_builtins import round

answered Aug 08 '13 at 00:49

Ignacio Vazquez-Abrams

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I tried "from future.modified_builtins import round" in my Python 2.7, and got ImportError says: No module named future.modified_builtins. I cannot get useful results about this "future.modified_builtins" library. Anything wrong here? – Tao Chen Aug 08 '13 at 06:20
Did you try installing it first? – Ignacio Vazquez-Abrams Aug 08 '13 at 06:21
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I didn't specifically install it. Only standard Python 2.7 and GAE libraries. – Tao Chen Aug 08 '13 at 06:25
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Thanks. I got it here: https://github.com/edschofield/python-future/blob/master/future/modified_builtins/newround.py I've thought it included in the standard 2.7 distribution. – Tao Chen Aug 08 '13 at 06:30
@TaoChen The link is no longer valid – Daksh Shah Jan 20 '18 at 19:05
What needs to be installed for this? Even after `sudo pip install future` it doesn't work – Daksh Shah Jan 20 '18 at 19:06
@DakshShah: `__future__` is part of the stdlib. – Ignacio Vazquez-Abrams Jan 20 '18 at 19:27

Implement Python 3's round function in Python 2.7

1 Answers1