unitkit

This Python package provides functionality for handling calculations involving values with units. It offers classes for defining units, values with units, and performing arithmetic operations on them.

Installation

The package can be installed directly from GitHub using pip:

pip install git+https://github.com/abates20/unitkit.git

Usage

Basic Usage

The package is primarily used via the Value object. This object is initialized with a number and a string specifying the units.

from unitkit import Value
my_value = Value(5, "kJ/kg")

Values can be converted to new units with the "convert_units" method or the "to" method for simpler syntax.

print(my_value.convert_units("BTU/lbm")) # Output: "2.1496153532127984 BTU lbm^-1"
print(my_value.to("BTU/lbm")) # Output: "2.1496153532127984 BTU lbm^-1"

Aritmethic Operations

Value objects can be used in arithmetic expressions (addition, subtraction, multiplication, division, exponentiation, etc.). The package keeps track of the units in the background along the way.

mass = Value(10, "kg")
acceleration = Value(5, "m/s^2")
force = mass * acceleration
print(force) # Output: "50.0 kg m s^-2"
print(force.to("N")) # Output: "50.0 N"

You can mix and match units from different systems (i.e., SI units and imperial units) when doing calculations. Again, the package keeps track of the units in the background.

rho = Value(50, "lbm/ft3")
mu = Value(0.001, "Pa*s")
v = Value(3, "km/hr")
D = Value(3, "in")
Re = rho * v * D / mu
print(Re) # Output: "450000.0 lbm km in hr^-1 Pa^-1 s^-1 ft^-3"
print(Re.to(None)) # Output: "50858.684950996845 (unitless)"

Additional Features

Some conversions require a molecular weight (e.g., converting from kg to kmol). These conversions can be done by providing a molecular weight as an argument to the "convert_units" and "to" methods.

molecular_weight = Value(10, "g/mol")
print(my_value.to("kJ/mol", molecular_weight)) # Output: "0.05 kJ mol^-1

The package also provides some support for significant figures (sigfigs). Value objects have a roundsf method for rounding based on the number of sigfigs.

my_value = Value(1.01, "kg")
print(my_value.roundsf(2)) # Output: "1.0 kg"