Round a ruby float up or down to the nearest 0.05

Question

I\'m getting numbers like

2.36363636363636
4.567563
1.234566465448465
10.5857447736

How would I get Ruby to round these numbers up (or dow

Answer 1

less precise, but this method is what most people are googling this page for

(5.65235534).round(2)
#=> 5.65

Answer 2

Ruby 2 now has a round function:

# Ruby 2.3
(2.5).round
 3

# Ruby 2.4
(2.5).round
 2

There are also options in ruby 2.4 like: :even, :up and :down e.g;

(4.5).round(half: :up)
 5

Answer 3

In general the algorithm for “rounding to the nearest x” is:

round(x / precision)) * precision

Sometimes is better to multiply by 1 / precision because it is an integer (and thus it works a bit faster):

round(x * (1 / precision)) / (1 / precision)

In your case that would be:

round(x * (1 / 0.05)) / (1 / 0.05)

which would evaluate to:

round(x * 20) / 20;

I don’t know any Python, though, so the syntax might not be correct but I’m sure you can figure it out.