Unit Handling with Pint Quantity

HyperSpy uses the pint library to handle unit conversion. To be interoperatable with other modules, HyperSpy uses the default pint pint.UnitRegistry provided by the pint.get_application_registry() function as described in the sections having a shared registry and serialization of the pint user guide.

For example, in the case of the scale_as_quantify pint quantity object from UniformDataAxis, the default pint pint.UnitRegistry is used:

>>> s = hs.signals.Signal1D(np.arange(10))
>>> s.axes_manager[0].scale_as_quantity
<Quantity(1.0, 'dimensionless')>
>>> s.axes_manager[0].scale_as_quantity = '2.5 µm'
>>> s.axes_manager[0].scale_as_quantity
<Quantity(2.5, 'micrometer')>

Then, using pint.get_application_registry() get the handle of the same instance of pint.UnitRegistry used by HyperSpy and use it to operate on this pint quantity:

>>> import pint
>>> ureg = pint.get_application_registry()
>>> scale = 2E-6 * ureg.meter
>>> s.axes_manager[0].scale_as_quantity += scale
>>> s.axes_manager[0].scale_as_quantity
<Quantity(4.5, 'micrometer')>