Filtering Structures¶

ASSYST filters are callables that accept an ase.Atoms structure and return a bool: True to keep the structure, False to drop it.

Because filters are plain callables, they work directly with Python’s built-in filter() function:

from assyst.filters import DistanceFilter, AspectFilter

structures = [...]   # list of ase.Atoms

dist_filter = DistanceFilter({"Fe": 1.1, "N": 0.7})
good = list(filter(dist_filter, structures))

Any callable with the signature (Atoms) -> bool is accepted wherever a Filter is expected — including plain functions and lambdas:

# keep only structures with at least 4 atoms
good = list(filter(lambda s: len(s) >= 4, structures))

Composing filters¶

FilterBase subclasses support & (and) and | (or) to build compound filters without nesting explicit AndFilter / OrFilter instances:

combined = DistanceFilter({"Fe": 1.1}) & AspectFilter(maximum_aspect_ratio=5)
good = list(filter(combined, structures))

The & operator short-circuits: the right-hand filter is only evaluated if the left-hand filter returns True.

Available filter classes¶

Class	What it checks
`DistanceFilter`	Minimum interatomic distances (element-pair cutoffs)
`AspectFilter`	Maximum aspect ratio of the unit cell (longest / shortest lattice parameter)
`VolumeFilter`	Maximum volume per atom
`EnergyFilter`	Energy per atom within `[min_energy, max_energy]` (requires a single-point `ase.calculators.calculator.Calculator`)
`ForceFilter`	Maximum atomic force magnitude (requires a single-point `ase.calculators.calculator.Calculator`)

See assyst.filters for the full API reference of each class.