Representation of quantites, i.e. of unit valued scalars and arrays. Rust library with Python bindings.
As opposed to other implementations, this crate does not attempt to achieve compile time checks on units. It is written with flexibility in mind and is able to represent arbitrarily complex units. Additional to simple scalar quantities, it also provides utilities for vector valued quantities, based on the ndarray crate, where all entries share the same unit.
You can install the python package either from pypi:
pip install quantity
of from source (you need a rust compiler for that):
pip install git+https://github.com/itt-ustutt/quantity
Add this to your Cargo.toml:
[dependencies]
quantity = "0.3"
Calculate pressure of an ideal gas.
python
from quantity import *
temperature = 25.0 * CELSIUS
volume = 1.5 * METER**3
moles = 75.0 * MOL
pressure = moles * RGAS * temperature / volume
print(pressure) # 123.94785148011941 kPa
numpy functions can be used with quantities:
python
from quantity import *
import numpy as np
ms = np.array([2.0, 3.0, 4.0]) * METER
sqms = np.square(ms)
print(sqms) # [4, 9, 16] m²
print(np.sqrt(sqms)) # [2, 3, 4] m
Calculate pressure of an ideal gas.
rust
let temperature = 25.0 * CELSIUS;
let volume = 1.5 * METER.powi(3);
let moles = 75.0 * MOL;
let pressure = moles * RGAS * temperature / volume;
println!("{:.5}", pressure); // 123.94785 kPa
Calculate the gravitational pull of the moon on the earth.
rust
let mass_earth = 5.9724e24 * KILOGRAM;
let mass_moon = 7.346e22 * KILOGRAM;
let distance = 383.398 * KILO * METER;
let force = G * mass_earth * mass_moon / distance.powi(2);
println!("{:.5e}", force); // 1.99208e26 N
Calculate the pressure distribution in the atmosphere using the barometric formula.
rust
let z = SIArray1::linspace(1.0 * METER, 70.0 * KILO * METER, 10)?;
let g = 9.81 * METER / SECOND.powi(2);
let m = 28.949 * GRAM / MOL;
let t = 10.0 * CELSIUS;
let p0 = BAR;
let pressure = p0 * (-&z * m * g).to_reduced(RGAS * t)?.mapv(f64::exp);
for i in 0..10 {
println!("z = {:8.5} p = {:9.5}", z.get(i), pressure.get(i));
}
// z = 1.00000 m p = 99.98794 kPa
// z = 7.77867 km p = 39.12796 kPa
// z = 15.55633 km p = 15.31182 kPa
// z = 23.33400 km p = 5.99192 kPa
// z = 31.11167 km p = 2.34480 kPa
// z = 38.88933 km p = 917.58301 Pa
// z = 46.66700 km p = 359.07479 Pa
// z = 54.44467 km p = 140.51557 Pa
// z = 62.22233 km p = 54.98750 Pa
// z = 70.00000 km p = 21.51808 Pa
For the rust documentation, see here. For the python documentation, see here.
To build the project including the bindings to python, we use maturin.
When developing, use
maturin develop --release --cargo-extra-args="--features python"
To build the python wheels, use
maturin build --release --cargo-extra-args="--features python"
To build the documentation you need sphinx and some additional packages. From the root directory, type
cd docs
make html
To run the doctests, from the root directory, type
cd docs
make doctest