smooth

Utilities for smoothing geometries.

Fork + Port of https://github.com/philipschall/shapelysmooth (Public domain)

InputeTypeError

Bases: TypeError

Raised when the input geometry is of the incorrect type.

Source code in src/rastr/gis/smooth.py

class InputeTypeError(TypeError):
    """Raised when the input geometry is of the incorrect type."""

catmull_rom_smooth(geometry, alpha=0.5, subdivs=10)

Polyline smoothing using Catmull-Rom splines.

Parameters:

Name	Type	Description	Default
geometry	BaseGeometry	The geometry to smooth	required
alpha	float	The tension parameter, between 0 and 1 inclusive. Defaults to 0.5. - For uniform Catmull-Rom splines, alpha = 0. - For centripetal Catmull-Rom splines, alpha = 0.5. - For chordal Catmull-Rom splines, alpha = 1.0.	0.5
subdivs	int	Number of subdivisions of each polyline segment. Default value: 10.	10

Returns: The smoothed geometry.

Source code in src/rastr/gis/smooth.py

def catmull_rom_smooth(
    geometry: BaseGeometry, alpha: float = 0.5, subdivs: int = 10
) -> LineString | Polygon:
    """Polyline smoothing using Catmull-Rom splines.

    Args:
        geometry: The geometry to smooth
        alpha: The tension parameter, between 0 and 1 inclusive. Defaults to 0.5.
               - For uniform Catmull-Rom splines, alpha = 0.
               - For centripetal Catmull-Rom splines, alpha = 0.5.
               - For chordal Catmull-Rom splines, alpha = 1.0.
        subdivs:
            Number of subdivisions of each polyline segment. Default value: 10.

    Returns: The smoothed geometry.
    """
    if not isinstance(geometry, (LineString, Polygon)):
        msg = "Only LineString and Polygon geometries are supported."
        raise NotImplementedError(msg)
    coords, interior_coords = _get_coords(geometry)
    coords_smoothed = _catmull_rom(coords, alpha=alpha, subdivs=subdivs)
    if isinstance(geometry, LineString):
        return geometry.__class__(coords_smoothed)
    elif isinstance(geometry, Polygon):
        interior_coords_smoothed = [
            _catmull_rom(c, alpha=alpha, subdivs=subdivs) for c in interior_coords
        ]
        return geometry.__class__(coords_smoothed, holes=interior_coords_smoothed)
    else:
        assert_never(geometry)