https://github.com/readysteady/percentage
Ruby gem for working with percentages
https://github.com/readysteady/percentage
bigdecimal percentage ruby
Last synced: about 2 months ago
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Ruby gem for working with percentages
- Host: GitHub
- URL: https://github.com/readysteady/percentage
- Owner: readysteady
- License: other
- Created: 2012-11-29T13:56:42.000Z (over 12 years ago)
- Default Branch: main
- Last Pushed: 2025-01-02T12:27:57.000Z (5 months ago)
- Last Synced: 2025-04-02T20:37:33.439Z (about 2 months ago)
- Topics: bigdecimal, percentage, ruby
- Language: Ruby
- Homepage: https://rubygems.org/gems/percentage
- Size: 51.8 KB
- Stars: 32
- Watchers: 1
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGES.md
- License: LICENSE.txt
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README
# percentage
Ruby gem for working with percentages.
## Install
Using Bundler:
$ bundle add percentage
Using RubyGems:
$ gem install percentage
## Constructing Percentages
The `Percentage` method converts numeric objects to percentage objects
with values that you would expect:
```ruby
Percentage(50) # => 50%
Percentage(BigDecimal('17.5')) # => 17.5%
Percentage(Rational(25, 2)) # => 12.5%
```
Percentage objects can also be constructed directly, but in this case
BigDecimal/Rational values are treated as fractions:
```ruby
Percentage.new(50) # => 50%
Percentage.new(BigDecimal('0.175')) # => 17.5%
Percentage.new(Rational(1, 8)) # => 12.5%
```
Some shortcut methods are defined on Integer and BigDecimal for convenience:
```ruby
50.percent # => 50%
5.as_percentage_of(10) # => 50.0%
BigDecimal('2.9').to_percentage # => 2.9%
```
## Numeric features
As with other numerics, percentage objects are conceptually immutable.
Common numeric functionality like `to_i`, `to_f`, `to_s`, `to_r`, `zero?`,
and equality/comparison methods are defined.
Percentages can be added together:
```ruby
Percentage(10) + Percentage(20) # => 30%
```
They can also be "scaled up" using the `scale` method:
```ruby
Percentage(10).scale(5) # => 50%
```
Multiplication is defined using the fractional value of the percentage.
BigDecimal objects can't be coerced into rational objects, so the
multiplication order will matter in some cases, for example:
```ruby
Percentage(50) * 10 # => (5/1)
Percentage(50) * Percentage(10) # => 5.0%
BigDecimal('150.00') * Percentage(50) # => BigDecimal('75.00')
Percentage(50) * BigDecimal('150.00') # raises TypeError
```
## Bonus extras
There's a #percent_of method defined on Integer and BigDecimal for percentage calculations:
```ruby
50.percent_of(BigDecimal(150)) # => BigDecimal('75.00')
10.percent_of(100) # => (10/1)
BigDecimal('0.5').percent_of(88) # => BigDecimal('0.44')
```
There's also a `Percentage.change` method for calculating the percentage change between two values:
```ruby
Percentage.change(2, 3) # => 50.0%
```