pynbody.filt.Disc

class pynbody.filt.Disc(radius: float | str | UnitBase, height: float | str | UnitBase, cen: _Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str] = (0, 0, 0))

Bases: Filter

A filter that selects particles within a disc of specified extent and thickness.

Methods

__call__(sim)	Return a boolean mask indicating which particles are in the filter.
cubic_cell_intersection(centroids)	Compute the intersection with cubic cells with the specified centroids.
where(sim)	Return the indices of particles that are in the filter.

__init__(radius: float | str | UnitBase, height: float | str | UnitBase, cen: _Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str] = (0, 0, 0))

Create a disc filter.

In keeping with other parts of pynbody, the disc is defined in the x-y plane, with the z-axis being the symmetry axis. This is useful in conjunction with automated disc alignment e.g. pynbody.analysis.angmom.sideon().

Parameters:

• radius – The radius of the disc (in the xy-plane). If a string, it is interpreted as a unit string.

• height – The thickness of the disc (in the z-direction). If a string, it is interpreted as a unit string.

• cen – The centre of the disc. If a pynbody.snapshot.simsnap.SimArray, units can be provided and will be correctly accounted for.

cubic_cell_intersection(centroids)

Compute the intersection with cubic cells with the specified centroids.

This is currently used by the swift loader to figure out which cells to load

where(sim: snapshot.SimSnap)

Return the indices of particles that are in the filter.

This is a convenience method that is equivalent to np.where(f(sim)) but may be more efficient for some filters.