Rounding a float number in python

Question

I have a float numer

a = 1.263597

I hope get

b = 1.2635

But when I try

round (a,4)

then result is

1.2636

What should I do?

Answer 1

Try math.floor with this small modification -

import math

def floor_rounded(n,d):
    return math.floor(n*10**d)/10**d

n = 1.263597
d = 4

output = floor_rounded(n,d)
print(output)

1.2635

For your example, you can just do math.floor(1.263597 * 10000)/10000

---

EDIT: Based on the valid comment by @Mark, here is another way of solving this, but this time forcing the custom rounding using string operations.

#EDIT: Alternate approach, based on the comment by Mark Dickinson

def string_rounded(n,d):
    i,j = str(n).split('.')
    return float(i+'.'+j[:d])

n = 8.04
d = 2

output = string_rounded(n,d)
output

8.04