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tortuosity

Compute the tortuosity of a line.

Note

Defined as the ratio of the actual path length to the straight-line (Euclidean) distance between its endpoints. Tortuosity is a measure of how convoluted or winding a line is. A perfectly straight line has a tortuosity of 1, while more winding lines have higher values.

Parameters:

Name Type Description Default
line Union[LineString, MultiLineString]

Input shapely LineString or MultiLineString object.

 required

Returns:

Name Type Description
float float

The tortuosity value of a line.
Source code in src/histolytics/spatial_geom/line_metrics.py 
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def tortuosity(line: Union[LineString, MultiLineString]) -> float:
    """Compute the tortuosity of a line.

    Note:
        Defined as the ratio of the actual path length to the straight-line (Euclidean)
        distance between its endpoints. Tortuosity is a measure of how convoluted or
        winding a line is. A perfectly straight line has a tortuosity of 1, while more
        winding lines have higher values.

    Parameters:
        line (Union[LineString, MultiLineString]):
            Input shapely LineString or MultiLineString object.

    Returns:
        float:
            The tortuosity value of a line.
    """
    if isinstance(line, LineString):
        path_length = line.length
        euclidean_distance = LineString([line.coords[0], line.coords[-1]]).length
        return path_length / euclidean_distance if euclidean_distance > 0 else None
    elif isinstance(line, MultiLineString):
        path_length = line.length
        # Find the correct start and end points by sorting the coordinates
        coords = [list(geom.coords) for geom in line.geoms]
        coords = [item for sublist in coords for item in sublist]
        sorted_coords = sorted(coords, key=lambda x: (x[0], x[1]))
        start_point = sorted_coords[0]
        end_point = sorted_coords[-1]
        euclidean_distance = LineString([start_point, end_point]).length
        return path_length / euclidean_distance if euclidean_distance > 0 else None
    else:
        return None