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