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https://github.com/zceemja/si-base
A basic python package that converts numerical strings with units to base units
https://github.com/zceemja/si-base
conversion jax numpy python scientific scipy
Last synced: about 1 month ago
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A basic python package that converts numerical strings with units to base units
- Host: GitHub
- URL: https://github.com/zceemja/si-base
- Owner: zceemja
- License: mit
- Created: 2021-11-03T10:27:25.000Z (about 3 years ago)
- Default Branch: master
- Last Pushed: 2022-08-04T14:40:35.000Z (over 2 years ago)
- Last Synced: 2023-12-16T15:15:07.957Z (11 months ago)
- Topics: conversion, jax, numpy, python, scientific, scipy
- Language: Python
- Homepage: https://pypi.org/project/sibase/
- Size: 28.3 KB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# SI-Base python package
A basic python package that converts numerical strings with units to base units.
There are two main classes:
* `Unit` which holds information about units, for instance that string `km/s` has unit **m** with *10 power of 3* and unit **s** with *10 power of -1*
* `Value` is a float which also holds Unit and some numerical value that is always in **SI Base**.
### Examples:
```python
from sibase import Value, Unit
value = Value('3e5 nm/ps') # 3e+08 m/s
# value is instance of float with value if 3e8
float_value = value.to('km/s') # 300000.0
# shorthand method:
float_value = value @ 'km/s'
# Converting with units:
float_value = Unit('km/s').convert(3e8)
# shorthand methods:
float_value = 3e8 @ Unit('km/s')
float_value = Unit('km/s') @ 3e8
# Operations
# Note that this only compares numerical values, not units
Value('50 km') > '1e6 mm' # True
Value('50 km') < '1e8 mm' # True
Value('50 /km') == '50 km^-1' # True
Value('50 km') + '50 km' # 1e5 m (returns Value object, keeps units from LHS)
Value('50 km') - '1e4 m' # 4e4 m (returns Value object, keeps units from LHS)
Value('50 km') * '100 m' # 5e6 m^2 (returns Value object, unit updated)
Value('1 km') / '50 m' # 20 (returns Value object, this case unitless)
Value('1 km') / '50 s' # 20 m/s (returns Value object, units updated)
# Invert operation returns string with original units
~Value('50 km') # 50 km
Value('50 km').original() # 50 km
# Reduces same unit and prefix values, useful for multiply/divide operations
Value('17 ps/nm/km/km').original(simplify=True) # 17 ps/nm/km^2
```
Superscripts are enabled by default
```python
from sibase import Value, Unit
Unit.USE_SUBSCRIPTS = False # Disable superscripts for units
Value('300mm^2/ps') # 3e+08 m²s⁻¹
```
Supports converting units with powers such as:
```python
from sibase import Value
Value('-21 ps^2/km') # -2.1e-26 s^2/m
Value('17 ps/nm/km') # 1.7e-05 s/m^2
# dB, dBm and Np (Nepers) are special units
Value('20 dB/km') # 0.1 /m
Value('2.3 km/Np') # ~10.05 m
Value('-20 dB') @ 'dBm' # 10.0
Value('0.2 dB/km') @ 'Np/m' # -3.43
# More special units can be added
from sibase import set_special_unit
set_special_unit(
'log', # name of unit
lambda x, _math: _math.log(x), # function to convert to SI base
lambda x, _math: _math.exp(x) # inverse of above
)
# Note: _math will depend on instance of x, it could be python's math module or numpy or jax.numpy
Value('10 log') # 2.30258509
Value('2.3') @ 'log' # ~10
Value('1π') # 3.14159265 ( π treated as special unit )
```
Numpy, probably could also applied for other libraries
```python
from sibase import to_base, Unit
import numpy as np
np_array = np.array([...])
# Convert from nonstandard:
si_array = to_base(np_array, 'km/s')
# Convert to other units
not_base_array = Unit('km/s').convert(si_array)
# shorthand method (will not work other way around for numpy arrays):
not_base_array = Unit('km/s') @ si_array
```