This library provide NumerichWithUnit class to calculate numeric easily with unit of measurement.
$ gem install numeric_with_unit
require 'numeric_with_unit'
#example 1
length = NumericWithUnit.new(10, 'm') # An object representing 10[m]
puts length #=> 10 m
puts length['cm'] #=> 1000/1 cm
# 'centi' is processed by Rational class in internal, the result also become Rational class.
time = 10.to_nwu('s') # Another way, use Fixnum#to_nwu. An object representing 10[s]
puts time #=> 10 s
puts time['min'] #=> 1/6 min
speed = length / time
puts speed #=> 6000/1 cm/min
puts speed['km/hr'] #=> 18/5 km/hr
require 'numeric_with_unit/util' # load utility script to describe with natural notation.
puts (10['m'] / 10['s'] )['km/hr'] #=> 18/5 km/hr
# example 2
puts (50['L/min'] + 3['m3/hr'] ) * 30['min'] #=> 3000/1 L
# example 3
puts 2["kg.um3/(m2.N)"] ** 0.5 #=> 1.4142135623730951e-09 s
# It is also possible to calculate the exponentiation roots of complex units.
- Caution:
Numeric#[],Fixnum#[]andBignum#[]are overrided whenrequire 'numeric_with_unit/util'
Unit of measurement is expressed in NumericWithUnit::Unit class. The basic unit (SI) is defined in 'numeric_with_unit/unit_definition/base.rb', and units derived from SI unit can be defined as follows.
# [kg], [m], [s] are predefined here.
NumericWithUnit::Unit['N'] = 'kg.m/s2' # definition of newton
NumericWithUnit::Unit['Pa'] = 'N/m2' # definition of pascal
NumericWithUnit::Unit['ton'] = 1000, 'kg' # definition of ton
If some unit is defined as a basic unit, it is not necessary to define units with prefixes (such as [cm]), units with exponents (such as [m2]) and assembly units (such as [m/s]).
In the above example, it is not necessary to define [kPa] or [Pa.s] (unit of viscosity) because [Pa] is defined.
The basic and common unit is predefined in 'numeric_with_unit/unit_definition/base.rb' and 'numeric_with_unit/unit_definition/common.rb' (These files are loaded by default)
NumericWithUnit::Unit.list.map(&:symbol) gives a list of defined units.
For Unit#[] and NumericWithUnit#[], you can pass a string representing the unit. For example.
- m
- cm
- m2
- kW.hr
- kg/cm2
- m.s-1
- J/kg/K
- kcal/(hr.m2.℃)
The basic unit with the prefix at the beginning and the exponent at the end is expressed in a form concatenated with "." or "/". You can also enclose it as a basic unit with "()".
The class representing "Unit of Measurement".
km = NumericWithUnit::Unit.new do |conf|
conf.symbol = 'km'
conf.dimension[:L] = 1
conf.from_si{|x| x/1000}
conf.to_si{|x| x*1000}
end
conf.from_si and conf.to_si configure the conversion formula expressing SI basic unit.
1 mi = 1.609344 km
Unit of relationship like above is generated by
mi = km.cast('mi', 1.609344)
It is only a proportional relationship.
Use Unit.new, to convert unit of relationship like ℃ and ℉.
Register unit as a basic unit by Unit << unit.
By registering as a basic unit, an assembly unit is automatically derived with Unit[].
NumericWithUnit::Unit << km
NumericWithUnit::Unit << NumericWithUnit::Unit.new do |conf|
conf.symbol = 'hr'
conf.dimension[:T] = 1
conf.from_si{|x| x/60/60}
conf.to_si{|x| x*60*60}
end
p NumericWithUnit::Unit['km2'] #=> #<NumericWithUnit::Unit:[km2] {:L=>2}>
p NumericWithUnit::Unit['km/hr'] #=> #<NumericWithUnit::Unit:[km/hr] {:L=>1, :T=>-1}>
Units registered as basic units are obtained with Unit.list.
Also, Unit[]= convert units and register them as basic units at the same time.
NumericWithUnit::Unit['kph'] = 'km/hr'
NumericWithUnit::Unit['ua'] = 1.495978706916e8, 'm'
The basic unit is defined in the following file.
Please require accordingly.
- 'numeric_with_unit/unit_definition/base' (SI unit, SI assembly unit and SI combination unit. It is
requireby default.) - 'numeric_with_unit/unit_definition/common' (Units seemed as common. It is
requireby default.) - 'numeric_with_unit/unit_definition/cgs' (incomplete)
- 'numeric_with_unit/unit_definition/imperial' (incomplete)
- 'numeric_with_unit/unit_definition/natural' (incomplete)
The class representing numeric with unit of measurement information.
It is able to unit convert, add, subtract, multiply, divide and raise a power.
A NumerichWithUnit object that have numeric of value and unit of measurement of unit is returned.
For unit, pass a string representing a unit or an object of Unit class.
NumericWithUnit.new(self, unit) is returned.
Numeric returned.
Unit object returned.
NumericWithUnit object converted to new_unit is returned.
NumericWithUnit::DimensionError will be raised if new_unit with different dimensions from self is specified.
self converted to new_unit and self is returned.
NumericWithUnit::DimensionError will be raised if new_unit with different dimensions from self is specified.
NumerichWithUnit object that have added or subtracted numeric and converted unit returned.
If other is not a NumericWithUnit class, other converted to dimensionless NumerichWithUnit object.
NumericWithUnit::DimensionError will be raised if other with different dimensions from self is specified.
NumerichWithUnit object that have multiplied or divided numeric and derived unit returned.
If other is not a NumericWithUnit class, other converted to dimensionless NumerichWithUnit object.
NumerichWithUnit object that have numeric raised to num and derived unit raised to num returned.
For user who hope reduce number of key press.
require 'numeric_with_unit/util2'
x = 1000.0.m # 1000.0[m]
t = 1800.0.s # 1800.0[s]
v = (x/t).km_hr # 2.0 [km/hr]
vis = 1.0.Pa.s # 1.0 [s.Pa]
puts vis.cP #=> 1000.0 cP