mirror of
https://github.com/jbranchaud/til
synced 2026-01-02 22:58:01 +00:00
39 lines
1.3 KiB
Markdown
39 lines
1.3 KiB
Markdown
# Rounding Numbers With Precision
|
|
|
|
Ruby's `Float#round` method gets the job done, but doesn't offer much
|
|
configurability. If you'd like to finely control how a rounded number will
|
|
display, `ActiveSupport::NumberHelper` offers
|
|
[`number_to_rounded`](https://api.rubyonrails.org/classes/ActiveSupport/NumberHelper.html#method-i-number_to_rounded).
|
|
|
|
When a precision is specified, it will apply to the fraction digits:
|
|
|
|
```ruby
|
|
> ActiveSupport::NumberHelper.number_to_rounded(1.0, precision: 2)
|
|
=> "1.00"
|
|
```
|
|
|
|
Unless you include `significant: true` in which case precision will refer to
|
|
the number of signficant digits:
|
|
|
|
```ruby
|
|
> ActiveSupport::NumberHelper.number_to_rounded(1.0, precision: 2, significant: true)
|
|
=> "1.0"
|
|
```
|
|
|
|
Because this is for display purposes, the return value is a string. You can
|
|
further specify that insignificant zeros are stripped from the result:
|
|
|
|
```ruby
|
|
> ActiveSupport::NumberHelper.number_to_rounded(1.0, precision: 2, significant: true, strip_insignificant_zeros: true)
|
|
=> "1"
|
|
```
|
|
|
|
And for completeness, here is an example of a number being rounded up:
|
|
|
|
```ruby
|
|
> ActiveSupport::NumberHelper.number_to_rounded(1.29, precision: 2, significant: true)
|
|
=> "1.3"
|
|
```
|
|
|
|
[source](https://api.rubyonrails.org/classes/ActiveSupport/NumberHelper.html#method-i-number_to_rounded)
|