CODEWITHSUNDEEP
pythonrounding
Manny_G
Manny_G

Reputation: 333

Round integer in python without using round()

I know that I can round to the closest multiple of 10 in python by using round(<int>, -1) Is there a way to do this without using this built in function?

Edit:

Thanks for the feedback! The answer using divmod() was interesting because I had never used divmod before. Just in case anyone wants to know on CodingBat the solution used modulo as was suggested in the comments. Here it is in case anyone is interested. 

def round10(num):
  mod = num % 10
  num -= mod
  if mod >= 5: num += 10
  return num

Upvotes: 1

Views: 3897

Answers (4)

Cold Diamondz
Cold Diamondz

Reputation: 521

I have a function that rounds n to the nearest multiple of d:

def cm(n,d,o="+"):
    p = d - (n % d)
    m = n % d
    nm = n - m
    np = n + p
    if p > m:
        return nm
    elif m > p:
        return np
    else:
        if o == "+":
            return np
        else:
            return nm

How to use: use cm(number, near multiple wanted, preferred direction in special cases)

Examples:

cm(8,10) = 10
cm(6,4,"-") = 4 #special case (n % d == d - n % d)
cm(6,4,"+") = 8 #special case
cm(6,4) = 8

Upvotes: 0

mgilson
mgilson

Reputation: 309891

divide by 10, int, multiply by 10.

Actually, you can do it without any builtins using the // operator:

>>> def round(x):
...     return (x//10)*10
... 
>>> round(15.)
10.0
>>> round(25.)
20.0

Of course, this always rounds down. If you want to round up for values with a remainder greater than 5, you could use divmod:

def round(x):
    n, remainder = divmod(x, 10)
    if remainder >= 5:
        n += 1
    return n * 10

Upvotes: 2

Robert Kajic
Robert Kajic

Reputation: 9077

Round down to the closest multiple of 10:

int(n / 10) * 10

Round up to the closest multiple of 10:

int((n + 10) / 10) * 10

Round to the closest multiple of ten:

(int(n / 10) + bool(n % 10 >= 5)) * 10

Upvotes: 0

salezica
salezica

Reputation: 76909

This rounds to the closest, not always up or always down:

def xround(n):
    return (n + 5) // 10 * 10

Upvotes: 2

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