ibex_bluesky_core.utils

Utilities for plans which are not plan stubs.

Members

NamedReadableAndMovable	Abstract class for type checking that an object is readable, named and movable.
calculate_polarisation	Calculate polarisation value and propagate uncertainties.
center_of_mass_of_area_under_curve	Compute the centre of mass of the area under a curve defined by a series of (x, y) points.
centred_pixel	Given a centre and range, return a contiguous range of pixels around the centre, inclusive.
get_pv_prefix	Return the PV prefix for the current instrument.
is_matplotlib_backend_qt	Return True if matplotlib is using a qt backend.

class ibex_bluesky_core.utils.NamedReadableAndMovable(*args, **kwargs)

Bases: Readable[Any], NamedMovable[Any], Protocol

Abstract class for type checking that an object is readable, named and movable.

ibex_bluesky_core.utils.calculate_polarisation(a: Variable | DataArray, b: Variable | DataArray) → Variable | DataArray

Calculate polarisation value and propagate uncertainties.

This function computes the polarisation given by the formula (a-b)/(a+b) and propagates the uncertainties associated with a and b.

Parameters:

• a – scipp Variable or DataArray

• b – scipp Variable or DataArray

Returns:

polarisation, (a - b) / (a + b), as a scipp Variable or DataArray

On SANS instruments e.g. LARMOR, A and B correspond to intensity in different DAE periods (before/after switching a flipper) and the output is interpreted as a neutron polarisation ratio.

On reflectometry instruments e.g. POLREF, the situation is the same as on LARMOR.

On muon instruments, A and B correspond to measuring from forward/backward detector banks, and the output is interpreted as a muon asymmetry.

ibex_bluesky_core.utils.center_of_mass_of_area_under_curve(x: ndarray[tuple[Any, ...], dtype[float64]], y: ndarray[tuple[Any, ...], dtype[float64]]) → tuple[float, float]

Compute the centre of mass of the area under a curve defined by a series of (x, y) points.

The “area under the curve” is a shape bounded by: - min(y), along the bottom edge - min(x), on the left-hand edge - max(x), on the right-hand edge - straight lines joining (x, y) data points to their nearest neighbours along the x-axis, along the top edge

This is implemented by geometric decomposition of the shape into a series of trapezoids, which are further decomposed into rectangular and triangular regions.

Returns a tuple of the centre of mass and the total area under the curve.

ibex_bluesky_core.utils.centred_pixel(centre: int, pixel_range: int) → list[int]

Given a centre and range, return a contiguous range of pixels around the centre, inclusive.

ie. a centre of 50 with a range of 3 will give [47, 48, 49, 50, 51, 52, 53]

Parameters:

• centre (int) – The centre pixel number.

• pixel_range (int) – The range of pixels either side to surround the centre.

Returns a list of pixel numbers.

ibex_bluesky_core.utils.get_pv_prefix() → str

Return the PV prefix for the current instrument.

ibex_bluesky_core.utils.is_matplotlib_backend_qt() → bool

Return True if matplotlib is using a qt backend.