Skip to content

Class: Density

The Density class is a subclass of Variable designed to represent the mass per unit volume of a substance. It ensures accurate calculations by storing all values internally in its base SI unit, kilograms per cubic meter (kg/m3).

Supported Units

The following units are supported for initialization and conversion.

Unit str Conversion Factor to Kilograms per Cubic Meter (kg/m3)
kilograms per cubic meter kg/m3 1
grams per cubic centimeter g/cm3 1000
grams per milliliter g/mL 1000
pounds per cubic foot lb/ft3 16.0185
pounds per cubic inch lb/in3 27679.9

Class Reference

class Density(value, units='kg/m3')

A class for handling density measurements with automatic unit conversion.

Parameters:

  • value : float or int
    The numeric value of the density. Must be a non-negative number.
  • units : str, default='kg/m3'
    The unit of the provided value. Must be one of the supported units.

Raises:

  • ValueError : If value is negative or units is not a valid unit.

Examples: 

# Create a Density object of 1000 kg/m^3 (the density of water)  
>>> d1 = Density(1000)

# Create a Density object of 1 g/cm^3  
>>> d2 = Density(1, "g/cm3")

Properties

Property Type Description
.value float The numeric value of the density, always in kilograms per cubic meter (kg/m3). This is the internal representation used for all calculations.
.original_value float The numeric value as provided during initialization.
.original_unit str The unit as provided during initialization.

Methods

to(target_unit)

Returns a new Density object converted to the target_unit. The original object remains unchanged.

Parameters:

  • target_unit : str
    The unit to convert to. Must be one of the supported units.

Returns:

  • Density
    A new Density object with the same value, represented in the target unit.

Raises:

  • ValueError : If target_unit is not a valid unit.

Examples: 

# Initialize a density of 1000 kg/m^3  
>>> water_density_kg = Density(1000)

# Convert to g/cm^3  
>>> water_density_g = water_density_kg.to("g/cm3")

>>> print(water_density_g)  
1.0 g/cm3

String Representation

  • __str__(self)
    Returns a human-readable string representation of the density, rounded to six decimal places, using its original value and unit.
  • __repr__(self)
    Returns an unambiguous string representation of the object.