BaseField

class lsst.images.fields.BaseField

Bases: ABC

An abstract base class for parametric or interpolated 2-d functions, generally representing some sort of calculated image.

Notes

The field hierarchy is closed to the types in this package, so we can enumerate all of the serializations and avoid any kind of extension system. All field types are immutable.

Field types implement the function call operator and both multiplication and division by a constant via operator overloading. See the named evaluate and multiply_constant methods (respectively) for more information about those operations.

This interface will probably change in the future to incorporate options for dealing with out-of-bounds positions. At present the behavior for such positions is implementation-specific and should not be relied upon.

Attributes Summary

bounds	The region over which this field can be evaluated (Bounds).
unit	The units of the field (astropy.units.UnitBase or None).

Methods Summary

__call__()	Call self as a function.
evaluate(*, x, y, quantity)	Evaluate at non-gridded points.
multiply_constant(factor)	Multiply by a constant, returning a new field of the same type.
render([bbox, dtype])	Create an image realization of the field.

Attributes Documentation

bounds

The region over which this field can be evaluated (Bounds).

unit

The units of the field (astropy.units.UnitBase or None).

Methods Documentation

__call__(*, x: ndarray, y: ndarray, quantity: Literal[False] = False) → ndarray

__call__(*, x: ndarray, y: ndarray, quantity: Literal[True]) → Quantity

__call__(*, x: ndarray, y: ndarray, quantity: bool) → ndarray | Quantity

Call self as a function.

abstract evaluate(*, x: ndarray, y: ndarray, quantity: bool) → ndarray | Quantity

Evaluate at non-gridded points.

Parameters

x

X coordinates to evaluate at.

y

Y coordinates to evaluate at; must be broadcast-compatible with x.

quantity

If True, return an astropy.units.Quantity instead of a numpy.ndarray. If unit is None, the returned object will be a dimensionless Quantity.

abstract multiply_constant(factor: float | Quantity | UnitBase) → Self

Multiply by a constant, returning a new field of the same type.

Parameters

factor

Factor to multiply by. When this has units, those should multiply self.unit or set the units of the returned field if self.unit is None.

abstract render(bbox: Box | None = None, *, dtype: type[Any] | dtype[Any] | _SupportsDType[dtype[Any]] | tuple[Any, Any] | list[Any] | _DTypeDict | str | None = None) → Image

Create an image realization of the field.

Parameters

bbox

Bounding box of the image. If not provided, self.bounds.bbox will be used.

dtype

Pixel data type for the returned image.