I know Rails has some nice helpers for date and time management. Is there an already-working project consisting of, or incorporating a clean DSL for standard units and their conversions? Any开发者_JAVA技巧 project with helpers for the conversion between the two systems' basic units of length and weight would work. Thank you!
Wow, there are quite a few more of these than I expected. Here is what I believe to be a complete list, in alphabetical order, with example usage stripped from their documentation. I also noted if I couldn't get them running locally.
Alchemist
require 'alchemist' Alchemist.setup 8.miles.to.meters 10.kilometers + 1.mile # 11.609344 kilometers
measurement
This one appears out of date, the last commit was 5 years ago, and it doesn't seem to run on 1.9.3 for me.
include Measurement::Length Inch.new(12).to_centimeters # => #<Measurement::Length::Centimeter:0x173c2b4 @units=30.48>
Phys-Units
require "phys/units" Q = Phys::Quantity U = Phys::Unit Q[1.23,'km'] + Q[4.56,'m'] #=> Phys::Quantity[1.23456,'km'] Q[123,'mile'] / Q[2,'hr'] #=> Phys::Quantity[61,'mile/hr'] Q[61,'miles/hr'].want('m/s') #=> Phys::Quantity[27.26944,'m/s'] Q[1.0,'are'] == Q[10,'m']**2 #=> true
Quantity
Note that this one states that it is not production ready in the README.
require 'quantity/all' 1.meter #=> 1 meter 1.meter.to_feet #=> 3.28083... foot c = 299792458.meters / 1.second #=> 299792458 meter/second newton = 1.meter * 1.kilogram / 1.second**2 #=> 1 meter*kilogram/second^2 newton.to_feet #=> 3.28083989501312 foot*kilogram/second^2 newton.convert(:feet) #=> 3.28083989501312 foot*kilogram/second^2 jerk_newton = newton / 1.second #=> 1 meter*kilogram/second^3 jerk_newton * 1.second == newton #=> true
SY
See Boris Stitnickey's answer.
ruby-measurement
require 'ruby-measurement' measurement = Measurement.parse('3 feet') # => 3.0 ft. measurement.convert_to(:yards) # => 1.0 yd. measurement.convert_to(:in) # => 36.0 in. measurement.convert_to(:inches) # => 36.0 in. measurement1 = Measurement.parse('3 feet') # => 3.0 ft. measurement2 = Measurement.parse('6 inch') # => 6.0 in. measurement1 + measurement2 # => 3.5 ft.
ruby-units
require 'ruby-units' unit = Unit("mm") # unit only (defaults to a scalar of 1) unit = Unit("1 mm") # create a simple unit unit = Unit("1 kg*m^2/s^2") # complex unit unit1 =~ unit2 # true if units are compatible unit1.compatible?(unit2) # true if units are compatible unit1 = unit >> "ft" # convert to 'feet' unit3 = unit1 + unit2 # resulting object will have the units of unit1 unit1 === unit2 # true if units and quantity are the same, even if 'equivalent' by <=> unit.convert_to('ft') # convert (unit1 + unit2).convert_to('ft') # converts result to 'ft'
Units for Ruby
require 'units' three_meters = 3.meters two_meters = 2.m one_inch = 1.inch 3.meters.to_inches # => 118.1103 inch 10.inches.to_mm # => 254.0 millimeter
Unitwise
require 'unitwise/ext' 1.yard == (1.foot * 3) # => true 1.quart < 1.liter # => true 2.meter + 3.inch - 1.yard # => <Unitwise::Measurement 1.1618 meter> 1.convert_to('kg.m2/s2') == 1.joule # => true (20.kg * 9.8.convert_to('m/s2')).to_pound_force # => <Unitwise::Measurement 44.06255284754326 pound_force> (300.horsepower * 60.second).to_calorie # => <Unitwise::Measurement 3208077.8414151203 calorie>
Van/Unit
Like another poster, I had trouble getting this working. However, you can see Jörg W Mittag's answer for usage.
As the author of Unitwise, it might be obvious that it's my favorite out of the group. I encourage you to at least check it out, though.
Try awesome Alchemist.
......
Take a look at Tom Sawyer's Van/Unit
This is from the homepage:
require 'van/units'
include Units
1.mile.to(feet)
1.acre.to(yd**2)
1.acre.to(sq_yd)
1.gallon.to(self.L)
1.lb.to(kg)
1.m.s.to(m.s)
1.sq_mi.to(km**2)
1.mile.to(km)
1.usd.to(twd)
1.bit/s + 8.bytes/s
Try gem install sy
require 'sy'
( 5.g * # a bullet of 5g
500.m.s(-1) ** 2 / # flying at a speed of 500m/s has kJ energy:
2 ).in( :kJ ) #=> 0.625
require 'sy/imperial'
1.mile.in :ft #=> 5280.0
1.acre.in :yd² #=> 4840.0
1.gallon.in :l #=> 4.54609
1.lb.in :kg #=> 0.45359237
1.mile².in :km² #=> 2.589988110336
SY::SPEED_OF_LIGHT.in "furlong.fortnight⁻¹" #=> 1802617499785.2544
I was unable to get Van/units to work - all it reports is:
/Library/Ruby/Gems/1.8/gems/vanunits-1.5.0/lib/van/units/base.rb:493:in `to': incompatible units for operation (TypeError) from unitstest.rb:4
When running
require 'rubygems'
require 'van/units'
include Van::Units puts
1.meter.to(feet)
I spent an hour unsuccessfully attempting to hack the source of van/units.
The older gem on which it is based worked out of the box:
http://ruby-units.rubyforge.org/ruby-units/
vanunits seems broken. i suggest to try
rubyunits (http://ruby-units.rubyforge.org/ruby-units/)
or
measurements (https://github.com/collectiveidea/measurement)
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