interpolate

interpolate(
    x,
    y,
    xout,
    method='linear',
    order=None,
    x_transform='none',
    y_transform='none',
    sort_order='ascending',
    extrapolate=False,
)

Interpolate a paired series.

Mirrors the C# Linear, CubicSpline, and Polynomial interpolaters of the Numerics library. x_transform, y_transform, and extrapolate are Linear-only in C# (neither CubicSpline nor Polynomial has a transform surface or an Extrapolate() method), so they must be left at their defaults for method="cubic_spline" or "polynomial".

Parameters

Name	Type	Description	Default
x	array_like	Equal-length knots.	required
y	array_like	Equal-length knots.	required
xout	array_like	Positions to interpolate at.	required
method	('linear', 'cubic_spline', 'polynomial')		"linear"
order	int	The polynomial order – there are order + 1 terms for each polynomial function. Required when method="polynomial"; must be None otherwise.	None
x_transform	('none', 'logarithmic', 'log', 'normal_z')	Linear-only. "logarithmic" and "log" are equivalent aliases for the same Transform.Logarithmic value everywhere a transform argument appears in this module (:func:interpolate, :func:interpolate_2d, :func:curve_interpolate, :func:tabular_function); "logarithmic" (matching the C# enum member name) is the spelling used in this package’s own examples and documentation.	"none"
y_transform	('none', 'logarithmic', 'log', 'normal_z')	Linear-only. "logarithmic" and "log" are equivalent aliases for the same Transform.Logarithmic value everywhere a transform argument appears in this module (:func:interpolate, :func:interpolate_2d, :func:curve_interpolate, :func:tabular_function); "logarithmic" (matching the C# enum member name) is the spelling used in this package’s own examples and documentation.	"none"
sort_order	('ascending', 'descending')	Describes x.	"ascending"
extrapolate	bool	Whether to extend the end segments beyond the knots. False (the default) clamps to the end knot, matching the C# Interpolate() default; True calls the C# Extrapolate() method instead. Linear-only.	False

Returns

Name	Type	Description
	numpy.ndarray	Same length as xout.

Examples

>>> from corehydropy import interpolate
>>> interpolate([1, 2, 3, 4], [10, 20, 30, 40], [1.5, 2.5])
array([15., 25.])
>>> interpolate([1, 2, 3, 4], [10, 20, 30, 40], [1.5, 2.5], method="cubic_spline")
array([15., 25.])
>>> interpolate([1, 2, 3, 4], [10, 20, 30, 40], [1.5, 2.5], method="polynomial", order=3)
array([15., 25.])