Class: WeatherData::Weather

Inherits:
Object
  • Object
show all
Defined in:
lib/weather_data/weather.rb

Constant Summary collapse

ATTRIBUTES = 
[
  :temperature,
  :humidity,
  :wind
].freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(attributes = {}) ⇒ Weather

Returns a new instance of Weather.



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# File 'lib/weather_data/weather.rb', line 36

def initialize(attributes = {})
  ATTRIBUTES.each do |attr|
    self.send(:"#{attr}=", attributes[attr])
  end
end

Class Method Details

.parse(s) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/weather_data/weather.rb', line 17

def self.parse(s)
  attributes = {}.tap do |attrs|
    {
      :temperature => Temperature, 
      :humidity    => Humidity, 
      :wind        => Wind
    }.each do |attr, parser|
      begin
        attrs[attr] = parser.parse(s)
      rescue ArgumentError
      end
    end
  end

  raise ArgumentError.new(%Q{"#{s}" doesn't contain weather data}) if attributes.empty?

  new(attributes)
end

Instance Method Details

#apparent_temperature ⇒ Object 



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# File 'lib/weather_data/weather.rb', line 66

def apparent_temperature
  if vapour_pressure && temperature
    t = temperature.to_celsius.degrees
    Temperature::Celsius.new(t + 0.33 * vapour_pressure - 0.7 * wind.to_f - 4.0)
  end
end

#dew_point ⇒ Object 



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# File 'lib/weather_data/weather.rb', line 42

def dew_point
  if humidity && temperature
    t       = temperature.to_celsius.degrees
    a, b, c = magnus_formula_constants(t)
    gamma   = Math.log(humidity / 100) + b * t / (c + t)

    Temperature::Celsius.new(c * gamma / (b - gamma))
  end
end

#humidity=(value) ⇒ Object 



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# File 'lib/weather_data/weather.rb', line 84

def humidity=(value)
  @humidity = case value
  when String
    Humidity.parse(value)
  when Humidity::Relative
    value
  else
    raise ArgumentError.new(%Q{#{value.inspect} must be String or an instance of WeatherData::Humidity::Relative})
  end
end

#humindex ⇒ Object 



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# File 'lib/weather_data/weather.rb', line 59

def humindex
  if temperature && dew_point
    t = temperature.to_celsius.degrees + 0.5555 * (6.11 * Math.exp(5417.753 * (1 / 273.16 - 1 / dew_point.to_kelvin.degrees)) - 10)
    t.celsius
  end
end

#temperature=(value) ⇒ Object 



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# File 'lib/weather_data/weather.rb', line 73

def temperature=(value)
  @temperature = case value
  when String
    Temperature.parse(value)
  when Temperature::Base
    value
  else
    raise ArgumentError.new(%Q{#{value.inspect} must be String or kind of WeatherData::Temperature::Base})
  end
end

#vapour_pressure ⇒ Object 



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# File 'lib/weather_data/weather.rb', line 52

def vapour_pressure
  if humidity
    t = temperature.to_celsius.degrees
    (humidity / 100.0) * 6.105 * Math.exp(17.27 * t / (237.7 + t))
  end
end