CODEWITHSUNDEEP
pythonmathrounding
acordero
acordero

Reputation: 45

Round up to the nearest 0.05

I want to round up a number to 2 decimals, for example:

16.34 -> 16.35
16.36 -> 16.40
16.31 -> 16.35
16.35 -> 16.35 -- NOT ROUND
16.40 -> 16.40 -- NOT ROUND

If the number ended in 1-4 round to 5 and if the number 6-9 then round up to 0 How i can round up= Thanks u

Upvotes: 1

Views: 1306

Answers (1)

wjandrea
wjandrea

Reputation: 32954

Multiply the number by 20 (the reciprocal of 0.05), round up with math.ceil, and divide by the reciprocal.

For example:

>>> from math import ceil
>>> r = 0.05 ** -1
>>> for n in (i/100 for i in range(10, 20)):
...     m = ceil(n*r) / r
...     print('{:.2f} -> {:.2f}'.format(n, m))
...
0.10 -> 0.10
0.11 -> 0.15
0.12 -> 0.15
0.13 -> 0.15
0.14 -> 0.15
0.15 -> 0.15
0.16 -> 0.20
0.17 -> 0.20
0.18 -> 0.20
0.19 -> 0.20

[Due credit to Jan Stránský's and Thomas Jager's comments for explaining the technique]

Edit: Revisiting this, I think it's equivalent to a) use 0.05 itself instead of its reciprocal, reversing the operations, and b) use negative floor division instead of ceil.

>>> r = 0.05
>>> for n in (i/100 for i in range(10, 20)):
...     m = n // -r * -r
...     print('{:.2f} -> {:.2f}'.format(n, m))
...

(same output)

Upvotes: 2

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