Round integers to the nearest 10

Question

I am trying to round integers in python  I looked at the built-in round   function but it seems that that rounds floats    My goal is to round integers to the closest multiple of 10  i e   5-  10  4-  0  95- 100  etc   5 and higher should round up  4 and lower should round down    This is the code I have that does this    def round int x       last dig   int str x  -1       if last dig  gt   5          x    10     return  x 10    10   Is this the best way to achieve what I want to achieve  Is there a built-in function that does this  Additionally  if this is the best way  is there anything wrong with the code that I missed in testing

User · Answer

I wanted to do the same thing  but with 5 instead of 10  and came up with a simple function  Hope it s useful   def roundToFive num       remaining   num   5     if remaining in range 0  3           return num - remaining     return num    5 - remaining

User · Answer

Slightly simpler   def round int x       return 10     x   5     10

User · Answer

Actually  you could still use the round function    gt  gt  gt  print round 1123 456789  -1  1120 0   This would round to the closest multiple of 10  To 100 would be -2 as the second argument and so forth

User · Answer

This function will round either be order of magnitude  right to left  or by digits the same way that format treats floating point decimal places  left to right   def intround n  p           rounds an intger  if  p  lt 0  p is a exponent of 10  if p gt 0  left to right digits         if p  0  return n     if p gt 0            ln len str n             p p-ln 1 if n lt 0 else p-ln     return  n   5   10   -p-1      10  -p   10  -p   gt  gt  gt  tgt 5555555  gt  gt  gt  d 2  gt  gt  gt  print   t   rounded to    places  n t   right to left  n t   left to right  format          tgt d intround tgt -d   intround tgt d       Prints  5555555 rounded to 2 places  5555600 right to left  5600000 left to right   You can also use Decimal class   import decimal import sys  def ri i  prec 6       ic long if sys version info major lt 3 else int     with decimal localcontext   as lct          if prec gt 0              lct prec prec         else              lct prec len str decimal Decimal i    prec           n ic decimal Decimal i  decimal Decimal  0        return n   On Python 3 you can reliably use round with negative places and get a rounded integer   def intround2 n  p           will fail with larger floating point numbers on Py2 and require a cast to an int         if p gt 0          return round n  p-len str n   1      else          return round n  p        On Python 2  round will fail to return a proper rounder integer on larger numbers because round always returns a float    gt  gt  gt  round 2  34  -5  17179900000 0                       OK  gt  gt  gt  round 2  64  -5  1 84467440737096e 19                wrong    The other 2 functions work on Python 2 and 3

User · Answer

if you want the algebric form and still use round for it it s hard to get simpler than   interval   5 n   4 print round n interval   interval

User · Answer

About the round     function returning a float  That float  double-precision in Python  is always a perfect representation of an integer  as long as it s in the range  -253  253    Pedants pay attention  it s not two s complement in doubles  so the range is symmetric about zero    See the discussion here for details

User · Answer

round   can take ints and negative numbers for places  which round to the left of the decimal   The return value is still a float  but a simple cast fixes that    gt  gt  gt  int round 5678 -1   5680  gt  gt  gt  int round 5678 -2   5700  gt  gt  gt  int round 5678 -3   6000

[python] Round integers to the nearest 10

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