我有以下MultiPolygon

MULTIPOLYGON (
(
(10.8849956 49.8901705, 10.8849507 49.8902499, 10.884969 49.8902588, 10.8851033 49.8903298, 10.8851183 49.8903132, 10.88512882654868 49.8903054, 10.8851246 49.8903054, 10.8851246 49.8902754, 10.8851546 49.8902754, 10.8851546 49.89028643275958, 10.8853289 49.8901612, 10.885421 49.8901035, 10.8854414638889 49.8900896, 10.8854205 49.8900896, 10.8854205 49.8900596, 10.8854505 49.8900596, 10.8854505 49.89008346226415, 10.885527 49.8900315, 10.885519 49.8899952, 10.8854851 49.8899903, 10.8853164 49.8899957, 10.8852419 49.8899981, 10.8851711 49.8899919, 10.8851165 49.8899814, 10.8850728 49.8899652, 10.8850692 49.8899713, 10.8849925 49.8900275, 10.8850251 49.890083, 10.8850275 49.8901159, 10.8850185 49.8901733, 10.8849956 49.8901705),
(10.8852028 49.8901715, 10.8852328 49.8901715, 10.8852328 49.8902015, 10.8852028 49.8902015, 10.8852028 49.8901715),
(10.8852889 49.8900884, 10.8853146 49.8900884, 10.8853146 49.8901184, 10.8853078 49.8901184, 10.8853078 49.8901337, 10.8852808 49.8901337, 10.8852808 49.8901463, 10.8852508 49.8901463, 10.8852508 49.8901346, 10.8852239 49.8901346, 10.8852239 49.8901046, 10.8852305 49.8901046, 10.8852305 49.8900815, 10.8852589 49.8900815, 10.8852589 49.8900812, 10.8852889 49.8900812, 10.8852889 49.8900884),
(10.8851133 49.890201, 10.8851433 49.890201, 10.8851433 49.890231, 10.8851133 49.890231, 10.8851133 49.890201),
(10.8849849 49.8902202, 10.8850149 49.8902202, 10.8850149 49.8902502, 10.8849849 49.8902502, 10.8849849 49.8902202)
),

(
(10.8852605 49.8901112, 10.8852605 49.8901115, 10.8852539 49.8901115, 10.8852539 49.8901163, 10.8852778 49.8901163, 10.8852778 49.8901112, 10.8852605 49.8901112)
)
)


如何获得包含每个(唯一)点的平面列表?列表项不必一定是Shapely Points,它们也可以是元组。我不太了解如何迭代此结构。

最佳答案

不幸的是,Shapely没有提供立即从MultiPolygon对象提取所有点的功能。相反,您必须首先iterate over individual polygons of a MultiPolygon,然后是extract individual points of each Polygon

一个人可以想出不同的方法来解决这个问题。例如,如果您知道所有多边形都没有孔,则只需执行以下操作:

points = []
for polygon in multipolygon:
    points.extend(polygon.exterior.coords[:-1])


注意[:-1],它防止重复第一个顶点。如果您希望使用一种更简洁的语法并且不关心每个多边形有一个重复的点,可以将其删除。
也可以使用带有两个循环的列表理解来一行编写:

points = [point for polygon in multipolygon for point in polygon.exterior.coords[:-1]]


或在itertools.chain.from_iterable的帮助下:

from itertools import chain

points = list(chain.from_iterable(polygon.exterior.coords[:-1] for polygon in multipolygon))




通常,当多边形可以包含孔时,例如,我们可以编写以下函数从内部环中提取坐标:

def to_coords(multipolygon):
    for polygon in multipolygon:
        yield from polygon.exterior.coords[:-1]
        yield from chain.from_iterable(interior.coords[:-1] for interior in polygon.interiors)


用法示例:

mp = MultiPolygon([Polygon([(0, 0), (1, 0), (1, 1), (0, 1)]),
                   Polygon([(2, 0), (3, 0), (3, 1), (2, 1)],
                           holes=[[(2.25, 0.25), (2.75, 0.25), (2.75, 0.75), (2.25, 0.75)]])])


python - 如何使用Shapely获取嵌套的MultiPolygon中每个点的列表-LMLPHP

points = list(to_coords(mp))
# [(0.0, 0.0), (1.0, 0.0), (1.0, 1.0), (0.0, 1.0),
#  (2.0, 0.0), (3.0, 0.0), (3.0, 1.0), (2.0, 1.0),
#  (2.25, 0.25), (2.75, 0.25), (2.75, 0.75), (2.25, 0.75)]




甚至可以对任何输入几何(Python≥3.7)将其通用化:

from functools import singledispatch
from itertools import chain
from typing import (List,
                    Tuple,
                    TypeVar)

from shapely.geometry import (GeometryCollection,
                              LinearRing,
                              LineString,
                              Point,
                              Polygon)
from shapely.geometry.base import (BaseGeometry,
                                   BaseMultipartGeometry)

Geometry = TypeVar('Geometry', bound=BaseGeometry)


@singledispatch
def to_coords(geometry: Geometry) -> List[Tuple[float, float]]:
    """Returns a list of unique vertices of a given geometry object."""
    raise NotImplementedError(f"Unsupported Geometry {type(geometry)}")


@to_coords.register
def _(geometry: Point):
    return [(geometry.x, geometry.y)]


@to_coords.register
def _(geometry: LineString):
    return list(geometry.coords)


@to_coords.register
def _(geometry: LinearRing):
    return list(geometry.coords[:-1])


@to_coords.register
def _(geometry: BaseMultipartGeometry):
    return list(set(chain.from_iterable(map(to_coords, geometry))))


@to_coords.register
def _(geometry: Polygon):
    return to_coords(GeometryCollection([geometry.exterior, *geometry.interiors]))


用法示例:

from shapely.geometry import (MultiLineString,
                              MultiPoint,
                              MultiPolygon)

geometry_objects = [Point(0, 0),
                    LineString([(0, 0), (1, 1)]),
                    LinearRing([(0, 0), (1, 0), (1, 1)]),
                    Polygon([(0, 0), (1, 0), (1, 1), (0, 1)],
                            holes=[[(0.25, 0.25), (0.75, 0.25), (0.75, 0.75), (0.25, 0.75)]]),
                    MultiPoint([(0, 0), (1, 1)]),
                    MultiLineString([LineString([(0, 0), (1, 1)]), LineString([(2, 0), (3, 1)])]),
                    MultiPolygon([Polygon([(0, 0), (1, 0), (1, 1), (0, 1)]),
                                  Polygon([(2, 0), (3, 0), (3, 1), (2, 1)],
                                          holes=[[(2.25, 0.25), (2.75, 0.25), (2.75, 0.75), (2.25, 0.75)]])]),
                    GeometryCollection([Point(0, 0), LineString([(0, 0), (1, 1)])])]

for geometry in geometry_objects:
    print(f"For {geometry.wkt}\nwe got:\n"
          f"{to_coords(geometry)}\n")


输出:

For POINT (0 0)
we got:
[(0.0, 0.0)]

For LINESTRING (0 0, 1 1)
we got:
[(0.0, 0.0), (1.0, 1.0)]

For LINEARRING (0 0, 1 0, 1 1, 0 0)
we got:
[(0.0, 0.0), (1.0, 0.0), (1.0, 1.0)]

For POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0), (0.25 0.25, 0.75 0.25, 0.75 0.75, 0.25 0.75, 0.25 0.25))
we got:
[(0.0, 1.0), (0.0, 0.0), (0.25, 0.25), (0.75, 0.25), (0.75, 0.75), (0.25, 0.75), (1.0, 0.0), (1.0, 1.0)]

For MULTIPOINT (0 0, 1 1)
we got:
[(0.0, 0.0), (1.0, 1.0)]

For MULTILINESTRING ((0 0, 1 1), (2 0, 3 1))
we got:
[(2.0, 0.0), (0.0, 0.0), (3.0, 1.0), (1.0, 1.0)]

For MULTIPOLYGON (((0 0, 1 0, 1 1, 0 1, 0 0)), ((2 0, 3 0, 3 1, 2 1, 2 0), (2.25 0.25, 2.75 0.25, 2.75 0.75, 2.25 0.75, 2.25 0.25)))
we got:
[(0.0, 1.0), (0.0, 0.0), (3.0, 0.0), (3.0, 1.0), (2.0, 1.0), (2.0, 0.0), (2.25, 0.25), (2.75, 0.25), (2.75, 0.75), (2.25, 0.75), (1.0, 0.0), (1.0, 1.0)]

For GEOMETRYCOLLECTION (POINT (0 0), LINESTRING (0 0, 1 1))
we got:
[(0.0, 0.0), (1.0, 1.0)]

关于python - 如何使用Shapely获取嵌套的MultiPolygon中每个点的列表,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/58844463/

10-13 08:56