curve_simplify

curve_simplify(
    x,
    y,
    method='rdp',
    tolerance=None,
    num_to_keep=None,
    look_ahead=None,
    order_x='ascending',
    order_y='ascending',
    strict_x=True,
    strict_y=True,
)

Simplify a paired x-y curve.

Mirrors the C# OrderedPairedData’s three curve-simplification algorithms: Douglas-Peucker (method="rdp", needs tolerance), Visvalingam-Whyatt (method="visvalingam", needs num_to_keep), and Lang (method="lang", needs tolerance and look_ahead). NOTE: unlike rdp/visvalingam, which always keep the curve’s first and last point, lang does not force-keep the trailing point – a real, verified-against-the-real-C#-library upstream behavior (see ordered_paired_data.hpp’s sixth transcription note), not a port bug.

Parameters

Name	Type	Description	Default
x	array_like	Equal-length curve ordinates, at least two elements.	required
y	array_like	Equal-length curve ordinates, at least two elements.	required
method	('rdp', 'visvalingam', 'lang')		"rdp"
tolerance	float	Perpendicular-distance tolerance; required for method "rdp" or "lang".	None
num_to_keep	int	Number of points to keep; required for method="visvalingam", and must be at least 2 (the algorithm always keeps the curve’s first and last point, and needs at least 3 ordinates to triangulate at every intermediate step).	None
look_ahead	int	The Lang algorithm’s look-ahead window; required for method="lang".	None
order_x	('ascending', 'descending', 'none')		"ascending"
order_y	('ascending', 'descending', 'none')		"ascending"
strict_x	bool		True
strict_y	bool		True

Returns

Name	Type	Description
	numpy.ndarray	An (n, 2) array with columns [x, y].

Examples

>>> from corehydropy import curve_simplify
>>> x = [0, 1.57, 3.14, 4.71, 6.28]
>>> y = [0, 1, 0, -1, 0]
>>> curve_simplify(x, y, method="rdp", tolerance=0.01, strict_y=False, order_y="none")
array([[ 0.  ,  0.  ],
       [ 1.57,  1.  ],
       [ 4.71, -1.  ],
       [ 6.28,  0.  ]])