round down to 0.05 in python( not round nearest)

Asked Nov 08 '16 at 17:53

Active Nov 08 '16 at 18:04

Viewed 172 times

I need to round down to 0.05 in python. I tried the following code

def round_down(x):
    return round(math.floor(x / 0.05) * 0.05, 2)

inputs = [1.1, 1.12, 1.14, 1.15, 1.17, 1.18, 2.04, 2.25, 2.549, 2.57, 2.65]

for i in inputs:
    print i, '=>', round_down(i)

results:

1.1 => 1.1
1.12 => 1.1
1.14 => 1.1
1.15 => 1.1*
1.17 => 1.15
1.18 => 1.15
2.04 => 2.0
2.25 => 2.25
2.549 => 2.5
2.57 => 2.55
2.65 => 2.6*

I got the expected values except *ed inputs. * - For the inputs 1.15 and 2.65 should be 1.15 and 2.65. But I got 1.1 and 2.6. How do I solve this problem?

edited Nov 08 '16 at 18:04

asked Nov 08 '16 at 17:53

Suresh Kumar

http://stackoverflow.com/questions/588004/is-floating-point-math-broken – Ignacio Vazquez-Abrams Nov 08 '16 at 17:56
@MichaelKohl I need to do round down, not round nearest – Suresh Kumar Nov 08 '16 at 18:00
You can tweak the value to get it above the threshold when it's slightly off, see http://stackoverflow.com/questions/6063755/increment-a-python-floating-point-value-by-the-smallest-possible-amount – Mark Ransom Nov 08 '16 at 18:04
Or http://stackoverflow.com/questions/10420848/how-do-you-get-the-next-value-in-the-floating-point-sequence – Mark Ransom Nov 08 '16 at 18:10

round down to 0.05 in python( not round nearest)

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