Python Rounding

Question

I'm working with latitude/longitudes that end in either .25 or .75. I want to prompt a user for a lat/lon and have the program round it to a lat/lon ending in .25 or .75. I cannot round to .00 or .5, ONLY .25 or .75.

For examaple, if a user enters 43.04, I need Python to round that to 43.25.

I'm using Enthought Canopy Python distribution and am new to Python. Any suggestions for this?

Hello! Welcome to StackOverflow James. If you google "rounding in python" I think that you will find your answer. — thesecretmaster, Oct 23 '15 at 21:35
What should something like `43.45` to round to? What about `43.5`? — Mark Dickinson, Oct 23 '15 at 21:40
You can multiply by 4, round to an integer and divide by 4. Not very elegant, but simple : `round(43.15 * 4) / 4.` returns `43.25`. You can also play with the modulo operator: `43.15 - (43.15 % 0.25)` but that will always round down. — Zanapher, Oct 23 '15 at 21:40
Solution on my paste... I can't answer this question, don't know why http://pastebin.com/6BhChkBN — xdola, Oct 23 '15 at 21:45
@xPino - You can't answer this question because answers are closed on duplicates. There are already answers on the linked question. — TigerhawkT3, Oct 23 '15 at 21:46
@TigerhawkT3: It's not clear that it's a duplicate, though. The OP seems to be asking about rounding to the nearest number that ends in .25 or .75, rather than just rounding to the nearest quarter. — Mark Dickinson, Oct 23 '15 at 21:48
If the OP indicates that he wants more than just quarter-intervals, I'll reopen it. — TigerhawkT3, Oct 23 '15 at 21:51
I understood the question has having customized intervals... — A.D, Oct 23 '15 at 21:52

A.D · Accepted Answer · 2015-10-23T21:53:52.777

This can work as a custom rounding function:

def customRound(num, d = [0.0, 0.25, 0.75, 1.0]): # you can change this list to any e.g. [0.0, 0.1, 0.4, 0.9, 1.0]
     dec = num%1
     r = num - dec
     round_dec = min([(abs(i - dec),i) for i in d])[1]
     return r + round_dec

You can use it like this:

>>> customRound(9.34)
9.25
>>> customRound(9.4)
9.25
>>> customRound(9.98)
10.0
>>> customRound(9.8)
9.75

Python Rounding

1 Answers1