Transforms

Particle transforms rescale each particle’s foot before a footprint is rasterized (see Particle Weighting (Transforms)). A transform is any object with apply(particles, context); the built-ins are pydantic models whose fields are their config.yaml keys.

Interface

stilt.ParticleTransform	Anything with apply(particles, context) -> DataFrame.
stilt.TransformContext	What a transform may know about the footprint it is applied for.

Built-in transforms

stilt.transforms.AveragingKernel	Weight each particle's foot by an averaging kernel at its release coordinate.
stilt.transforms.PressureWeighting	Weight each particle by the fraction of the column's air mass it represents.
stilt.transforms.FirstOrderLifetime	Decay each particle's foot by exp(-age / lifetime).
stilt.transforms.UnresolvedTransform	A transform whose class could not be imported.

Science helpers

stilt.transforms.release_coordinate	Return each particle's release value of coordinate, indexed by indx.
stilt.transforms.particle_pwf	Derive each particle's release pressure and pressure weight.
stilt.transforms.ak_weights	Interpolate an averaging kernel to each row's particle release coordinate.

Loading and dumping

stilt.transforms.load_transform	Return a transform for one config entry.
stilt.transforms.dump_transform	Return the config mapping for one transform (inverse of load_transform()).
stilt.transforms.apply_transforms	Apply transforms in order; returns particles itself when there are none.