Easy way to round off to the nearest whole number with python3

How to calculate by rounding at the decimal point position specified by python3

I'll forget it soon, so I'll write it down as a reminder. ** There is round () ** Rounding after the decimal point is easy, but I didn't know.

• Truncate and round up with the math module (see reference link)

The default is

python3

>>> a = 1
>>> b = 6
>>> a / b
0.16666666666666666

Use the round function

python3

>>> round((a / b), 1)
0.2
>>> round((a / b), 2)
0.17
>>> round((a / b), 3)
0.167
>>> round((a / b), 4)
0.1667

Postscript

There was a lack of consideration, so I will add it.

In python3 series, it was sometimes not rounded well due to rounding. Note because I was addicted to rounding python3 This person was also resolved. It was very helpful including explanations.

• Since the lamda described here was a solution with one digit after the decimal point, this article supports two or more digits.

For example, it is like this that inconvenience occurs in just round.

python3

>>> round(1.1115, 3)
1.111
>>> round(1.1125, 3)
1.113

Including such cases, I think that it is possible to round off float types of arbitrary length with the following functions.

• There may be a shortage of tests, so please point out any problems.

python3

def custom_round(number, ndigits=0):
    if type(number) == int:#If it is an integer, return it as it is
        return number
    d_point = len(str(number).split('.')[1])#Define how many digits are after the decimal point
    if ndigits >= d_point:#If the value after the decimal point is larger than the argument, return it as it is.
        return number
    c = (10 ** d_point) * 2
    #Value for doubling the number of digits after the decimal point by adding 0 to the original number to make it an integer(0.If 01, c is 200)
    return round((number * c + 1) / c, ndigits)
    #Add 0 to the original number to make an integer, double it, add 1 and divide by 2. The original number is 0.01 is 0.Set to 015 and round

Execution example

>>> round(1.1115, 3)
1.111
>>> round(1.1125, 3)
1.113
>>>
>>> custom_round(1.1115, 3)
1.112
>>> custom_round(1.1125, 3)
1.113
>>> round(4.5)
4
>>> round(3.5)
4
>>> custom_round(4.5)
5.0
>>> custom_round(3.5)
4.0

Reference link

[Python / Sample / Manipulation of values after the decimal point, rounding, rounding, and truncation](http://ll.just4fun.biz/?Python/%E3%82%B5%E3%83%B3%E3%83%97 % E3% 83% AB /% E5% B0% 8F% E6% 95% B0% E7% 82% B9% E4% BB% A5% E4% B8% 8B% E3% 81% AE% E5% 80% A4% E3% 81% AE% E6% 93% 8D% E4% BD% 9C% E3% 83% BB% E5% 9B% 9B% E6% 8D% A8% E4% BA% 94% E5% 85% A5% E3% 82% 84% E5% 88% 87% E4% B8% 8A% E3% 81% 92% E3% 80% 81% E5% 88% 87% E6% 8D% A8% E3% 81% A6) Honke (2. Built-in functions #round ()) Note because I was addicted to rounding python3