openHAB

Class: OpenHAB::Core::Types::QuantityType

Inherits:
Object
  • Object
show all
Includes:
NumericType
Defined in:
lib/openhab/core/types/quantity_type.rb

Overview

QuantityType extends DecimalType to handle physical unit measurement.

QuantityType is part of the Units of Measurement framework in openHAB. It is represented as a decimal number with a unit. You can construct a QuantityType object by using the pipe operator with any Numeric.

Examples:

QuantityTypes can perform math operations between them.

(50 | "°F") + (-25 | "°F") # => 25.0 °F
(100 | "°F") / (2 | "°F") # => 50
(50 | "°F") - (25 | "°F") # => 25 °F
(50 | "°F") + (50 | "°F") # => 100 °F

If the operand is a number, it will be unit-less, but the result of the operation will have a unit. This only works for multiplication and division.

(50 | "°F") * 2 # => 100 °F
(100 | "°F") / 2 # => 50 °F

If the operand is a dimensioned NumberItem it will automatically be converted to a quantity for the operation.

# NumberF = "2 °F"
# NumberC = "2 °C"
(50 | "°F") + NumberF.state # => 52.0 °F
(50 | "°F") + NumberC.state # => 85.60 °F

If the operand is a non-dimensioned NumberItem it can be used only in multiplication and division operations.

# Number Dimensionless = 2
(50 | "°F") * Dimensionless.state # => 100 °F
(50 | "°F") / Dimensionless.state # => 25 °F

Quantities can be compared, if they have comparable units.

(50 | "°F") >  (25 | "°F")
(50 | "°F") >  (525 | "°F")
(50 | "°F") >= (50 | "°F")
(50 | "°F") == (50 | "°F")
(50 | "°F") <  (25 | "°C")

A Range can be used with QuantityType:

((0 | "°C")..(100 | "°C")).cover?(NumberC)

A Range can also be used in a case statement for a dimensioned item:

description = case NumberC.state
              when (-20 | "°C")...(18 | "°C") then "too cold"
              when (18 | "°C")...(25 | "°C") then "comfortable"
              when (25 | "°C")...(40 | "°C") then "too warm"
              else "out of range"
              end

Dimensioned Number Items can be converted to quantities with other units using the | operator

# NumberC = "23 °C"

# Using a unit
logger.info("In Fahrenheit #{NumberC.state | ImperialUnits::FAHRENHEIT }")

# Using a string
logger.info("In Fahrenheit #{NumberC.state | "°F"}")

Dimensionless Number Items can be converted to quantities with units using the | operator

# Dimensionless = 70

# Using a unit
logger.info("In Fahrenheit #{Dimensionless.state | ImperialUnits::FAHRENHEIT }")

# Using a string
logger.info("In Fahrenheit #{Dimensionless.state | "°F"}")

Dimensioned Number Items automatically use their units and convert automatically for math operations

# Number:Temperature NumberC = 23 °C
# Number:Temperature NumberF = 70 °F
NumberC.state - NumberF.state # => 1.88 °C
NumberF.state + NumberC.state # => 143.40 °F

Dimensionless Number Items can be used for multiplication and division.

# Number Dimensionless = 2
# Number:Temperature NumberF = 70 °F
NumberF.state * Dimensionless.state # => 140.0 °F
NumberF.state / Dimensionless.state # => 35.0 °F
Dimensionless.state * NumberF.state # => 140.0 °F
2 * NumberF.state                   # => 140.0 °F

Comparisons work on dimensioned number items with different, but comparable units.

# Number:Temperature NumberC = 23 °C
# Number:Temperature NumberF = 70 °F
NumberC.state > NumberF.state # => true

For certain unit types, such as temperature, all unit needs to be normalized to the comparator for all operations when combining comparison operators with dimensioned numbers.

(NumberC.state | "°F") - (NumberF.state | "°F") < 4 | "°F"

See Also:

Instance Method Summary collapse

Methods included from NumericType

#+@, #eql?, #to_d, #to_f, #to_i

Instance Method Details

#-@ ⇒ Object

arithmetic operators



171
 
# File 'lib/openhab/core/types/quantity_type.rb', line 171

alias_method :-@, :negate

#<=>(other) ⇒ Integer?

Comparison

Comparisons against Numeric and DecimalType are allowed only within a unit block to avoid unit ambiguities. Comparisons against other types may be done if supported by that type's coercion.

Parameters:

Returns:

  • (Integer, nil) —

    -1, 0, +1 depending on whether other is less than, equal to, or greater than self

    nil is returned if the two values are incomparable.



134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
 
# File 'lib/openhab/core/types/quantity_type.rb', line 134

def <=>(other)
  logger.trace("(#{self.class}) #{self} <=> #{other} (#{other.class})")
  case other
  when self.class
    return unitize(other.unit).compare_to(other) if unit == Units::ONE
    return compare_to(other.unitize(unit)) if other.unit == Units::ONE

    return compare_to(other)
  when Numeric, DecimalType
    if (unit = OpenHAB::DSL.unit(dimension))
      return compare_to(QuantityType.new(other, unit))
    end

    return nil # don't allow comparison with numeric outside a unit block
  end

  return nil unless other.respond_to?(:coerce)

  other.coerce(self)&.then { |lhs, rhs| lhs <=> rhs }
end

#coerce(other) ⇒ Array<(QuantityType, QuantityType)>?

Type Coercion

Coerce object to a OpenHAB::Core::Types::QuantityType

Parameters:

Returns:



163
164
165
166
167
168
 
# File 'lib/openhab/core/types/quantity_type.rb', line 163

def coerce(other)
  logger.trace("Coercing #{self} as a request from #{other.class}")
  return unless other.respond_to?(:to_d)

  [QuantityType.new(other.to_d.to_java, Units::ONE), self]
end

#to_invertible_unit(unit) ⇒ QuantityType Also known as: |

Convert this OpenHAB::Core::Types::QuantityType into another unit.

Examples:

NumberC.state | ImperialUnits::FAHRENHEIT

Parameters:

Returns:



10
 
# File 'lib/openhab/core/types/quantity_type.rb', line 10

def to_invertible_unit(unit); end