shapely.union

union(a, b, grid_size=None, **kwargs)

Merges geometries into one.

If grid_size is nonzero, input coordinates will be snapped to a precision grid of that size and resulting coordinates will be snapped to that same grid. If 0, this operation will use double precision coordinates. If None, the highest precision of the inputs will be used, which may be previously set using set_precision. Note: returned geometry does not have precision set unless specified previously by set_precision.

Parameters:

aGeometry or array_like

bGeometry or array_like

grid_sizefloat, optional

Precision grid size; requires GEOS >= 3.9.0. Will use the highest precision of the inputs by default.

**kwargs

For other keyword-only arguments, see the NumPy ufunc docs.

See also

union_all

set_precision

Examples

>>> from shapely import box, LineString, normalize
>>> line = LineString([(0, 0), (2, 2)])
>>> union(line, LineString([(2, 2), (3, 3)]))
<MULTILINESTRING ((0 0, 2 2), (2 2, 3 3))>
>>> union(line, None) is None
True
>>> box1 = box(0, 0, 2, 2)
>>> box2 = box(1, 1, 3, 3)
>>> normalize(union(box1, box2))
<POLYGON ((0 0, 0 2, 1 2, 1 3, 3 3, 3 1, 2 1, 2 0, 0 0))>
>>> box1 = box(0.1, 0.2, 2.1, 2.1)
>>> union(box1, box2, grid_size=1)
<POLYGON ((2 0, 0 0, 0 2, 1 2, 1 3, 3 3, 3 1, 2 1, 2 0))>