colour.Extrapolator#

class colour.Extrapolator(interpolator: Optional[TypeInterpolator] = None, method: Union[Literal['Linear', 'Constant'], str] = 'Linear', left: Optional[Real] = None, right: Optional[Real] = None, dtype: Optional[Type[DTypeReal]] = None, *args: Any, **kwargs: Any)[source]#

Bases: object

Extrapolate the 1-D function of given interpolator.

The colour.Extrapolator class acts as a wrapper around a given Colour or scipy interpolator class instance with compatible signature. Two extrapolation methods are available:

Linear: Linearly extrapolates given points using the slope defined by the interpolator boundaries (xi[0], xi[1]) if x < xi[0] and (xi[-1], xi[-2]) if x > xi[-1].
Constant: Extrapolates given points by assigning the interpolator boundaries values xi[0] if x < xi[0] and xi[-1] if x > xi[-1].

Specifying the left and right arguments takes precedence on the chosen extrapolation method and will assign the respective left and right values to the given points.

Parameters:

interpolator (Optional[TypeInterpolator]) – Interpolator object.
method (Union[Literal['Linear', 'Constant'], str]) – Extrapolation method.
left (Optional[Real]) – Value to return for x < xi[0].
right (Optional[Real]) – Value to return for x > xi[-1].
dtype (Optional[Type[DTypeReal]]) – Data type used for internal conversions.
args (Any) –
kwargs (Any) –

Methods

__init__()
__class__()

Notes

The interpolator must define x and y properties.

References

[sastanin], [WRC12b]

Examples

Extrapolating a single numeric variable:

>>> from colour.algebra import LinearInterpolator
>>> x = np.array([3, 4, 5])
>>> y = np.array([1, 2, 3])
>>> interpolator = LinearInterpolator(x, y)
>>> extrapolator = Extrapolator(interpolator)
>>> extrapolator(1)
-1.0

Extrapolating an ArrayLike variable:

>>> extrapolator(np.array([6, 7, 8]))
array([ 4.,  5.,  6.])

Using the Constant extrapolation method:

>>> x = np.array([3, 4, 5])
>>> y = np.array([1, 2, 3])
>>> interpolator = LinearInterpolator(x, y)
>>> extrapolator = Extrapolator(interpolator, method="Constant")
>>> extrapolator(np.array([0.1, 0.2, 8, 9]))
array([ 1.,  1.,  3.,  3.])

Using defined left boundary and Constant extrapolation method:

>>> x = np.array([3, 4, 5])
>>> y = np.array([1, 2, 3])
>>> interpolator = LinearInterpolator(x, y)
>>> extrapolator = Extrapolator(interpolator, method="Constant", left=0)
>>> extrapolator(np.array([0.1, 0.2, 8, 9]))
array([ 0.,  0.,  3.,  3.])

__init__(interpolator: Optional[TypeInterpolator] = None, method: Union[Literal['Linear', 'Constant'], str] = 'Linear', left: Optional[Real] = None, right: Optional[Real] = None, dtype: Optional[Type[DTypeReal]] = None, *args: Any, **kwargs: Any) → None[source]#

Parameters:

interpolator (Optional[TypeInterpolator]) –
method (Union[Literal['Linear', 'Constant'], str]) –
left (Optional[Real]) –
right (Optional[Real]) –
dtype (Optional[Type[DTypeReal]]) –
args (Any) –
kwargs (Any) –

Return type:

None

property interpolator: TypeInterpolator#

Getter and setter property for the Colour or scipy interpolator class instance.

Parameters:: value – Value to set the Colour or scipy interpolator class instance with.
Returns:: Colour or scipy interpolator class instance.
Return type:: TypeInterpolator

__weakref__#: list of weak references to the object (if defined)

property method: Union[Literal['Linear', 'Constant'], str]#

Getter and setter property for the extrapolation method.

Parameters:: value – Value to set the extrapolation method. with.
Returns:: Extrapolation method.
Return type:: str

property left: Optional[Real]#

Getter and setter property for left value to return for x < xi[0].

Parameters:: value – Left value to return for x < xi[0].
Returns:: Left value to return for x < xi[0].
Return type:: None or Real

property right: Optional[Real]#

Getter and setter property for right value to return for x > xi[-1].

Parameters:: value – Right value to return for x > xi[-1].
Returns:: Right value to return for x > xi[-1].
Return type:: None or Real

__call__(x: ArrayLike) → NDArrayFloat[source]#

Evaluate the Extrapolator at given point(s).

Parameters:: x (ArrayLike) – Point(s) to evaluate the Extrapolator at.
Returns:: Extrapolated points value(s).
Return type:: numpy.ndarray