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utils

Modules:

Name Description
detailed_balance
fit_target
plotting
utils

Functions:

Name Description
detailed_balance_factor

Compute the detailed balance factor (DBF): $$ DBF(E, T) = E(n(E)+1)=\frac{E}{(1 - e^{-E /

slicerplot_with_residuals

Create a SlicerPlot with an additional subplot for residuals.

Functions:

detailed_balance_factor(energy, temperature, energy_unit='meV', temperature_unit='K', divide_by_temperature=True)

Compute the detailed balance factor (DBF): $$ DBF(E, T) = E(n(E)+1)=\frac{E}{(1 - e^{-E / (k_B*T)})}}, $$ where \(n(E)\) is the Bose-Einstein distribution, \(E\) is the energy transfer, and \(T\) is the temperature. \(k_B\) is the Boltzmann constant. If divide_by_temperature is True, the result is normalized by \(k_B*T\) to have value 1 at \(E=0\).

Parameters:

Name Type Description Default
energy float | list | np.ndarray | sc.Variable

The energy transfer. If number, assumed to be in meV unless energy_unit is set.

required
temperature float | sc.Variable | Parameter

The temperature. If number, assumed to be in K unless temperature_unit is set.

required
energy_unit str | sc.Unit

Unit for energy if energy is given as a number or list.

'meV'
temperature_unit str | sc.Unit

Unit for temperature if temperature is given as a number.

'K'
divide_by_temperature bool

If True, divide the result by \(k_B*T\) to make it dimensionless and have value 1 at E=0. By default, True.

True

Raises:

Type Description
TypeError

If energy or temperature is not a number, list, numpy array, or scipp Variable, or if energy_unit or temperature_unit is not a string or scipp Unit, or if divide_by_temperature is not a boolean.

ValueError

If temperature is negative, or if energy is a numpy array with more than 1 dimension, or if temperature is a scipp Variable that does not have a single dimension named 'temperature', or if energy is a scipp Variable that does not have a single dimension named 'energy'.

UnitError

If the provided energy_unit or temperature_unit is invalid, or if the units of energy or temperature cannot be converted to the expected units.

ZeroDivisionError

If divide_by_temperature is True and temperature is zero.

Returns:

Type Description
np.ndarray

Detailed balance factor evaluated at the given energy and temperature.

Examples:

Basic usage

from easydynamics.utils.detailed_balance import detailed_balance_factor

dbf = detailed_balance_factor(1.0, 300)  # 1 meV at 300 K

Specifying units and disabling temperature normalisation

dbf = detailed_balance_factor(
    energy=[1.0, 2.0],
    temperature=300,
    energy_unit='microeV',
    temperature_unit='K',
    divide_by_temperature=False,
)

slicerplot_with_residuals(dg, *, residuals_key='Residuals', keep=None, operation='sum', **kwargs)

Create a SlicerPlot with an additional subplot for residuals.

This function is called internally by Analysis.plot_data_and_model and Analysis1d.plot_data_and_model. It can also be used directly with any sc.DataGroup that contains a residuals array.

Examples:

Plotting data, model, and residuals from a DataGroup

import scipp as sc
from easydynamics.utils.plotting import slicerplot_with_residuals

dg = sc.DataGroup({
    'Data': my_data,
    'Model': my_model,
    'Residuals': my_residuals,
})
fig = slicerplot_with_residuals(dg, residuals_key='Residuals', keep='energy')

Parameters:

Name Type Description Default
dg sc.DataGroup

DataGroup containing the data to plot. Must include a key for residuals.

required
residuals_key str

Key in the DataGroup that contains the residuals data.

'Residuals'
keep list[str] | str | None

Dimensions to keep in the SlicerPlot. Passed to SlicerPlot.

None
operation str

Operation to apply when reducing the residuals data. Passed to SlicerPlot.

'sum'
**kwargs object

Additional keyword arguments passed to SlicerPlot.

{}

Returns:

Type Description
InteractiveFigure

A figure containing the SlicerPlot and the residuals subplot.

Raises:

Type Description
TypeError

If dg is not a sc.DataGroup or if residuals_key is not a string.

ValueError

If residuals_key is not found in the DataGroup.

Modules

detailed_balance

Functions:

Name Description
detailed_balance_factor

Compute the detailed balance factor (DBF): $$ DBF(E, T) = E(n(E)+1)=\frac{E}{(1 - e^{-E /

Classes

Functions:

detailed_balance_factor(energy, temperature, energy_unit='meV', temperature_unit='K', divide_by_temperature=True)

Compute the detailed balance factor (DBF): $$ DBF(E, T) = E(n(E)+1)=\frac{E}{(1 - e^{-E / (k_B*T)})}}, $$ where \(n(E)\) is the Bose-Einstein distribution, \(E\) is the energy transfer, and \(T\) is the temperature. \(k_B\) is the Boltzmann constant. If divide_by_temperature is True, the result is normalized by \(k_B*T\) to have value 1 at \(E=0\).

Parameters:

Name Type Description Default
energy float | list | np.ndarray | sc.Variable

The energy transfer. If number, assumed to be in meV unless energy_unit is set.

required
temperature float | sc.Variable | Parameter

The temperature. If number, assumed to be in K unless temperature_unit is set.

required
energy_unit str | sc.Unit

Unit for energy if energy is given as a number or list.

'meV'
temperature_unit str | sc.Unit

Unit for temperature if temperature is given as a number.

'K'
divide_by_temperature bool

If True, divide the result by \(k_B*T\) to make it dimensionless and have value 1 at E=0. By default, True.

True

Raises:

Type Description
TypeError

If energy or temperature is not a number, list, numpy array, or scipp Variable, or if energy_unit or temperature_unit is not a string or scipp Unit, or if divide_by_temperature is not a boolean.

ValueError

If temperature is negative, or if energy is a numpy array with more than 1 dimension, or if temperature is a scipp Variable that does not have a single dimension named 'temperature', or if energy is a scipp Variable that does not have a single dimension named 'energy'.

UnitError

If the provided energy_unit or temperature_unit is invalid, or if the units of energy or temperature cannot be converted to the expected units.

ZeroDivisionError

If divide_by_temperature is True and temperature is zero.

Returns:

Type Description
np.ndarray

Detailed balance factor evaluated at the given energy and temperature.

Examples:

Basic usage

from easydynamics.utils.detailed_balance import detailed_balance_factor

dbf = detailed_balance_factor(1.0, 300)  # 1 meV at 300 K

Specifying units and disabling temperature normalisation

dbf = detailed_balance_factor(
    energy=[1.0, 2.0],
    temperature=300,
    energy_unit='microeV',
    temperature_unit='K',
    divide_by_temperature=False,
)

fit_target

Classes:

Name Description
FitTarget

One fittable prediction of a model, bound to a key in a parameters Dataset.

Classes

FitTarget(name, dataset_key, function, label, x_unit, y_unit) dataclass

One fittable prediction of a model, bound to a key in a parameters Dataset.

Models declare their predictions by returning FitTargets (see DiffusionModelBase.get_fit_targets), and FitBinding maps them onto the dataset keys they should be fitted against. Instances are immutable snapshots created on demand, so the units always reflect the model state at the time the targets are built.

Attributes:

Name Type Description
name str

The prediction's name (e.g. 'width', 'area', 'delta_area', 'value').

dataset_key str | None

The key in the parameters Dataset holding the data this prediction is fitted against. None when the prediction has no default key (component models); FitBinding supplies the key in that case.

function Callable

The fit function; called as function(x) with raw x values expressed in x_unit and returning raw values expressed in y_unit.

label str

Display label used for plots and results (e.g. 'DeltaLorentz width').

x_unit str | None

The unit function expects its input in, or None if no unit conversion applies.

y_unit str | None

The unit of function's output, or None if no unit conversion applies.

plotting

Functions:

Name Description
slicerplot_with_residuals

Create a SlicerPlot with an additional subplot for residuals.

Functions:

slicerplot_with_residuals(dg, *, residuals_key='Residuals', keep=None, operation='sum', **kwargs)

Create a SlicerPlot with an additional subplot for residuals.

This function is called internally by Analysis.plot_data_and_model and Analysis1d.plot_data_and_model. It can also be used directly with any sc.DataGroup that contains a residuals array.

Examples:

Plotting data, model, and residuals from a DataGroup

import scipp as sc
from easydynamics.utils.plotting import slicerplot_with_residuals

dg = sc.DataGroup({
    'Data': my_data,
    'Model': my_model,
    'Residuals': my_residuals,
})
fig = slicerplot_with_residuals(dg, residuals_key='Residuals', keep='energy')

Parameters:

Name Type Description Default
dg sc.DataGroup

DataGroup containing the data to plot. Must include a key for residuals.

required
residuals_key str

Key in the DataGroup that contains the residuals data.

'Residuals'
keep list[str] | str | None

Dimensions to keep in the SlicerPlot. Passed to SlicerPlot.

None
operation str

Operation to apply when reducing the residuals data. Passed to SlicerPlot.

'sum'
**kwargs object

Additional keyword arguments passed to SlicerPlot.

{}

Returns:

Type Description
InteractiveFigure

A figure containing the SlicerPlot and the residuals subplot.

Raises:

Type Description
TypeError

If dg is not a sc.DataGroup or if residuals_key is not a string.

ValueError

If residuals_key is not found in the DataGroup.

utils

Functions:

Name Description
verify_Q_index

Verify that Q_index is a valid integer index into Q.

convert_units_with_rollback

Apply a sequence of unit conversions, rolling all of them back if any fails.

convert_value_unit

Convert a numeric value from one unit to another without mutating anything.

convert_parameter_unit

Convert a parameter to a new unit, keeping dependent parameters consistent.

energy_to_scipp

Convert a numpy energy array to a scipp Variable with dimension 'energy'.

Classes

Functions:

verify_Q_index(Q_index, Q, allow_none=False)

Verify that Q_index is a valid integer index into Q.

When Q is None (e.g. no data has been loaded yet), only the type and sign of Q_index are checked; the upper-bound check is deferred until Q is available.

Parameters:

Name Type Description Default
Q_index int

Index to validate.

required
Q sc.Variable | None

The Q values (may be None if no data is loaded).

required
allow_none bool

Whether or not to allow Q_index to be None

False

Raises:

Type Description
TypeError

If Q_index is not an int (or not an int or None when allow_none=True).

IndexError

If Q_index is negative, or out of range when Q is available.

convert_units_with_rollback(conversions)

Apply a sequence of unit conversions, rolling all of them back if any fails.

Each item is (convert, new_unit, old_unit) where convert is a callable applying a unit (e.g. a bound convert_x_unit or a functools.partial around :func:convert_parameter_unit). The conversions are applied in order; if any raises, every item is converted back to its old unit best-effort (converting a not-yet-converted item back to its old unit is a no-op) and the original exception is re-raised.

Parameters:

Name Type Description Default
conversions list[tuple[Callable[[str | sc.Unit], None], str | sc.Unit, str | sc.Unit]]

The conversions to apply, each as (convert, new_unit, old_unit).

required

Raises:

Type Description
Exception

Whatever the failing conversion raised, after the rollback attempt.

convert_value_unit(value, from_unit, to_unit)

Convert a numeric value from one unit to another without mutating anything.

Returns the value unchanged when the two units compare equal as strings (the common no-conversion case, kept cheap for hot paths).

Parameters:

Name Type Description Default
value float

The value to convert.

required
from_unit str | sc.Unit

The unit the value is currently expressed in.

required
to_unit str | sc.Unit

The unit to convert the value to.

required

Returns:

Type Description
float

The value expressed in to_unit.

convert_parameter_unit(parameter, unit)

Convert a parameter to a new unit, keeping dependent parameters consistent.

Independent parameters are converted with convert_unit. Dependent parameters are converted with set_desired_unit, so the new unit survives later dependency-graph recomputations (a plain convert_unit would be reverted to the old desired unit the next time the dependency expression is re-evaluated).

Parameters:

Name Type Description Default
parameter Parameter

The parameter to convert.

required
unit str | sc.Unit

The unit to convert to.

required
energy_to_scipp(energy, unit)

Convert a numpy energy array to a scipp Variable with dimension 'energy'.

Parameters:

Name Type Description Default
energy np.ndarray

The energy array to be converted

required
unit str | sc.Unit

The unit of the energy

required

Returns:

Type Description
sc.Variable

Energy as sc.Variable.