pynbody.filt.Sphere

class pynbody.filt.Sphere(radius: 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 radius of the point cen.

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, cen: _Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str] = (0, 0, 0))

Create a sphere filter.

Parameters:

• radius – The radius of the sphere. If a string, it is interpreted as a unit string.

• cen – The centre of the sphere. 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)

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.