Function offset_curve

shapely/constructive.py:271–342

Return a (Multi)LineString at a distance from the object. For positive distance the offset will be at the left side of the input line. For a negative distance it will be at the right side. In general, this function tries to preserve the direction of the input. Note: the behaviour r

(
    geometry, distance, quad_segs=8, join_style="round", mitre_limit=5.0, **kwargs
)

)
@multithreading_enabled
def offset_curve(
    geometry, distance, quad_segs=8, join_style="round", mitre_limit=5.0, **kwargs
):
    """Return a (Multi)LineString at a distance from the object.

    For positive distance the offset will be at the left side of the input
    line. For a negative distance it will be at the right side. In general,
    this function tries to preserve the direction of the input.

    Note: the behaviour regarding orientation of the resulting line depends
    on the GEOS version. With GEOS < 3.11, the line retains the same
    direction for a left offset (positive distance) or has opposite direction
    for a right offset (negative distance), and this behaviour was documented
    as such in previous Shapely versions. Starting with GEOS 3.11, the
    function tries to preserve the orientation of the original line.

    Parameters
    ----------
    geometry : Geometry or array_like
        Geometry or geometries for which to compute the offset.
    distance : float or array_like
        Specifies the offset distance from the input geometry. Negative
        for right side offset, positive for left side offset.
    quad_segs : int, default 8
        Specifies the number of linear segments in a quarter circle in the
        approximation of circular arcs.
    join_style : {'round', 'bevel', 'mitre'}, default 'round'
        Specifies the shape of outside corners. 'round' results in
        rounded shapes. 'bevel' results in a beveled edge that touches the
        original vertex. 'mitre' results in a single vertex that is beveled
        depending on the ``mitre_limit`` parameter.
    mitre_limit : float, default 5.0
        Crops of 'mitre'-style joins if the point is displaced from the
        buffered vertex by more than this limit.
    **kwargs
        See :ref:`NumPy ufunc docs <ufuncs.kwargs>` for other keyword arguments.

    Notes
    -----

    .. deprecated:: 2.1.0
        A deprecation warning is shown if ``quad_segs``, ``join_style`` or
        ``mitre_limit`` are specified as positional arguments. In a future
        release, these will need to be specified as keyword arguments.

    Examples
    --------
    >>> import shapely
    >>> from shapely import LineString
    >>> line = LineString([(0, 0), (0, 2)])
    >>> shapely.offset_curve(line, 2)
    <LINESTRING (-2 0, -2 2)>
    >>> shapely.offset_curve(line, -2)
    <LINESTRING (2 0, 2 2)>

    """
    if isinstance(join_style, str):
        join_style = BufferJoinStyle.get_value(join_style)