Class: Data::Pressure

Inherits:
Units
  • Object
show all
Defined in:
lib/barometer/data/pressure.rb

Overview

A simple Pressure class

Think of this like the Integer class. Enhancement is that you can create a number (in a certain unit), then get that number back already converted to another unit.

All comparison operations will be done in metric

NOTE: the metric units for pressure aren’t commonly used, except

that this class was designed for storing weather data,
and it seems that it is more common in this case

Constant Summary collapse

METRIC_UNITS = 
"mb"
IMPERIAL_UNITS = 
"in"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(metric = true) ⇒ Pressure

Returns a new instance of Pressure.



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# File 'lib/barometer/data/pressure.rb', line 22

def initialize(metric=true)
  @millibars = nil
  @inches = nil
  super(metric)
end

Instance Attribute Details

#inches ⇒ Object

Returns the value of attribute inches.



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# File 'lib/barometer/data/pressure.rb', line 20

def inches
  @inches
end

#millibars ⇒ Object

Returns the value of attribute millibars.



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# File 'lib/barometer/data/pressure.rb', line 20

def millibars
  @millibars
end

Class Method Details

.in_to_mb(inches) ⇒ Object 



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# File 'lib/barometer/data/pressure.rb', line 40

def self.in_to_mb(inches)
  return nil unless inches &&
    (inches.is_a?(Integer) || inches.is_a?(Float))
  inches.to_f * 33.8639
end

.mb_to_in(mb) ⇒ Object

CONVERTERS



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# File 'lib/barometer/data/pressure.rb', line 35

def self.mb_to_in(mb)
  return nil unless mb && (mb.is_a?(Integer) || mb.is_a?(Float))
  mb.to_f * 0.02953
end

Instance Method Details

#<=>(other) ⇒ Object

OPERATORS



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# File 'lib/barometer/data/pressure.rb', line 84

def <=>(other)
  self.mb <=> other.mb
end

#imperial_default=(value) ⇒ Object 



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# File 'lib/barometer/data/pressure.rb', line 29

def imperial_default=(value); self.in = value; end

#in(as_integer = true) ⇒ Object

return the stored inches or convert from millibars



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# File 'lib/barometer/data/pressure.rb', line 75

def in(as_integer=true)
  inches = (@inches || Data::Pressure.mb_to_in(@millibars))
  inches ? (as_integer ? inches.to_i : (100*inches).round/100.0) : nil
end

#in=(inches) ⇒ Object

store inches



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# File 'lib/barometer/data/pressure.rb', line 60

def in=(inches)
  return if !inches || !(inches.is_a?(Integer) || inches.is_a?(Float))
  @inches = inches.to_f
  self.update_millibars(inches.to_f)
end

#mb(as_integer = true) ⇒ Object

return the stored millibars or convert from inches



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# File 'lib/barometer/data/pressure.rb', line 68

def mb(as_integer=true)
  mb = (@millibars || Data::Pressure.in_to_mb(@inches))
  mb ? (as_integer ? mb.to_i : (100*mb).round/100.0) : nil
end

#mb=(mb) ⇒ Object

store millibars



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# File 'lib/barometer/data/pressure.rb', line 52

def mb=(mb)
  return if !mb || !(mb.is_a?(Integer) || mb.is_a?(Float))
  @millibars = mb.to_f
  self.update_inches(mb.to_f)
end

#metric_default=(value) ⇒ Object 



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# File 'lib/barometer/data/pressure.rb', line 28

def metric_default=(value); self.mb = value; end

#nil? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/barometer/data/pressure.rb', line 138

def nil?
  (@millibars || @inches) ? false : true
end

#to_f(metric = nil) ⇒ Object

will just return the value (no units) with more precision



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# File 'lib/barometer/data/pressure.rb', line 100

def to_f(metric=nil)
  (metric || (metric.nil? && self.metric?)) ? self.mb(false) : self.in(false)
end

#to_i(metric = nil) ⇒ Object

will just return the value (no units)



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# File 'lib/barometer/data/pressure.rb', line 94

def to_i(metric=nil)
  (metric || (metric.nil? && self.metric?)) ? self.mb : self.in
end

#to_s(metric = nil) ⇒ Object

will return the value with units



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# File 'lib/barometer/data/pressure.rb', line 106

def to_s(metric=nil)
  (metric || (metric.nil? && self.metric?)) ? "#{self.mb} #{METRIC_UNITS}" : "#{self.in} #{IMPERIAL_UNITS}"
end

#units(metric = nil) ⇒ Object

will just return the units (no value)



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# File 'lib/barometer/data/pressure.rb', line 112

def units(metric=nil)
  (metric || (metric.nil? && self.metric?)) ? METRIC_UNITS : IMPERIAL_UNITS
end

#update_inches(mb) ⇒ Object

when we set millibars, it is possible the a non-equivalent value of inches remains. if so, clear it.



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# File 'lib/barometer/data/pressure.rb', line 130

def update_inches(mb)
  return unless @inches
  difference = Data::Pressure.mb_to_in(mb.to_f) - @inches
  # only clear inches if the stored inches is off be more then 1 unit
  # then the conversion of millibars
  @inches = nil unless difference.abs <= 1.0
end

#update_millibars(inches) ⇒ Object

when we set inches, it is possible the a non-equivalent value of millibars remains. if so, clear it.



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# File 'lib/barometer/data/pressure.rb', line 119

def update_millibars(inches)
  return unless @millibars
  difference = Data::Pressure.in_to_mb(inches.to_f) - @millibars
  # only clear millibars if the stored millibars is off be more then 1 unit
  # then the conversion of inches
  @millibars = nil unless difference.abs <= 1.0
end