libpysal.cg.Polygon¶
- class libpysal.cg.Polygon(vertices, holes=None)[source]¶
Geometric representation of polygon objects. Returns a polygon created from the objects specified.
- Parameters:
- vertices
python:list A list of vertices or a list of lists of vertices.
- holes
python:list A list of sub-polygons to be considered as holes. Default is
None.
- vertices
Examples
>>> p1 = Polygon([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))])
- Attributes:
verticespython:listReturns the vertices of the polygon in clockwise order.
lenpython:intReturns the number of vertices in the polygon.
perimeterpython:floatReturns the perimeter of the polygon.
bounding_boxlibpysal.cg.RectangleReturns the bounding box of the polygon.
bboxpython:listReturns the bounding box of the polygon as a list.
areapython:floatReturns the area of the polygon.
centroidpython:tupleReturns the centroid of the polygon.
Methods
__init__(vertices[, holes])Build the quad tree structure for this polygon.
contains_point(point)Test if a polygon contains a point.
Attributes
Returns the area of the polygon.
Returns the bounding box of the polygon as a list.
Returns the bounding box of the polygon.
Returns the centroid of the polygon.
Returns the holes of the polygon in clockwise order.
Returns the number of vertices in the polygon.
Returns the parts of the polygon in clockwise order.
Returns the perimeter of the polygon.
Returns the vertices of the polygon in clockwise order.
- property area: float¶
Returns the area of the polygon.
Examples
>>> p = Polygon([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))]) >>> p.area 1.0
>>> p = Polygon( ... [Point((0, 0)), Point((10, 0)), Point((10, 10)), Point((0, 10))], ... [Point((2, 1)), Point((2, 2)), Point((1, 2)), Point((1, 1))] ... ) >>> p.area 99.0
- property bbox¶
Returns the bounding box of the polygon as a list.
- Returns:
- self._bbox
python:list The bounding box of the polygon as a list.
- self._bbox
See also
libpysal.cg.bounding_box
- property bounding_box¶
Returns the bounding box of the polygon.
- Returns:
- self._bounding_box
libpysal.cg.Rectangle The bounding box of the polygon.
- self._bounding_box
Examples
>>> p = Polygon([Point((0, 0)), Point((2, 0)), Point((2, 1)), Point((0, 1))]) >>> p.bounding_box.left 0.0
>>> p.bounding_box.lower 0.0
>>> p.bounding_box.right 2.0
>>> p.bounding_box.upper 1.0
- build_quad_tree_structure()[source]¶
Build the quad tree structure for this polygon. Once the structure is built, speed for testing if a point is inside the ring will be increased significantly.
- property centroid: tuple¶
Returns the centroid of the polygon.
Notes
The centroid returned by this method is the geometric centroid and respects multipart polygons with holes. Also known as the ‘center of gravity’ or ‘center of mass’.
Examples
>>> p = Polygon( ... [Point((0, 0)), Point((10, 0)), Point((10, 10)), Point((0, 10))], ... [Point((1, 1)), Point((1, 2)), Point((2, 2)), Point((2, 1))] ... ) >>> p.centroid (5.0353535353535355, 5.0353535353535355)
- contains_point(point)[source]¶
Test if a polygon contains a point.
- Parameters:
- point
libpysal.cg.Point A point to test for containment.
- point
- Returns:
- containsbool
Trueif the polygon containspointotherwiseFalse.
Notes
Points falling exactly on polygon edges may yield unpredictable results.
Examples
>>> p = Polygon( ... [Point((0,0)), Point((4,0)), Point((4,5)), Point((2,3)), Point((0,5))] ... ) >>> p.contains_point((3,3)) 1
>>> p.contains_point((0,6)) 0
>>> p.contains_point((2,2.9)) 1
>>> p.contains_point((4,5)) 0
>>> p.contains_point((4,0)) 0
Handles holes.
>>> p = Polygon( ... [Point((0, 0)), Point((0, 10)), Point((10, 10)), Point((10, 0))], ... [Point((2, 2)), Point((4, 2)), Point((4, 4)), Point((2, 4))] ... ) >>> p.contains_point((3.0, 3.0)) False
>>> p.contains_point((1.0, 1.0)) True
- property holes: list¶
Returns the holes of the polygon in clockwise order.
Examples
>>> p = Polygon( ... [Point((0, 0)), Point((10, 0)), Point((10, 10)), Point((0, 10))], ... [Point((1, 2)), Point((2, 2)), Point((2, 1)), Point((1, 1))] ... ) >>> len(p.holes) 1
- property len: int¶
Returns the number of vertices in the polygon.
Examples
>>> p1 = Polygon([Point((0, 0)), Point((0, 1)), Point((1, 1)), Point((1, 0))]) >>> p1.len 4
>>> len(p1) 4
- property parts: list¶
Returns the parts of the polygon in clockwise order.
Examples
>>> p = Polygon( ... [ ... [Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))], ... [Point((2, 1)), Point((2, 2)), Point((1, 2)), Point((1, 1))] ... ] ... ) >>> len(p.parts) 2
- property perimeter: int | float¶
Returns the perimeter of the polygon.
Examples
>>> p = Polygon([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))]) >>> p.perimeter 4.0
- property vertices: list¶
Returns the vertices of the polygon in clockwise order.
Examples
>>> p1 = Polygon([Point((0, 0)), Point((0, 1)), Point((1, 1)), Point((1, 0))]) >>> len(p1.vertices) 4