Converting Pint Quantities To YAML and back with YAML tags in Pint

yaml_ize_pint.py

import pint
import yaml
u = pint.UnitRegistry(system='mks', autoconvert_offset_to_baseunit=True)

def units_representer(dumper, data):
    return dumper.represent_scalar(u'!u', str(data))
yaml.add_representer(u.Quantity, units_representer)

def units_constructor(loader, node):
    value = loader.construct_scalar(node)
    mag, units = value.split(' ')
    return u.Quantity(float(mag), units)
yaml.add_constructor(u'!u', units_constructor)

q = 5*u.meter
print("The raw pint quantity:", q)
#The raw pint quantity: 5 meter

yaml_string = yaml.dump(q)
print("The resulting yaml:", yaml_string)
#The resulting yaml: !u '5 meter'

q_reborn = yaml.load(yaml_string)
print("The reloaded quantity with some math done on it", q_reborn**2)
#The reloaded quantity with some math done on it 25.0 meter ** 2