Pregunta Dibuja una elipse usando Shapely


Estoy integrando Bien proporcionado en mi código, y tengo que lidiar con varios tipos diferentes de objetos geométricos. La mayoría de mis necesidades están satisfechas con Lines, Polygons y LineStrings, pero necesito usar elipsis. ¿Hay alguna manera de crear una elipse en forma de un cuadro delimitador o de un semieje, sin tener que discretizar la elipse en líneas?

¡Aclamaciones!


10
2017-10-28 02:32


origen


Respuestas:


No hay ninguna forma de representar un polígono en Shapely sin discretizarlo.

En el nivel base, Shapely se ocupa de los puntos. Todo, desde LineString hasta Polygon, es solo una lista de puntos. Un buen ejemplo de esto es lo que sucede cuando tomas un Point y amortiguarlo:

>>> import shapely
>>> from shapely.geometry.point import Point
>>> p = Point(0, 0)
>>> circle = p.buffer(1.0)
>>> list(circle.exterior.coords)
[(1.0, 0.0), (0.99518472667219693, -0.098017140329560506), (0.98078528040323054, -0.19509032201612808), (0.95694033573220894, -0.29028467725446211), (0.92387953251128696, -0.38268343236508939), (0.88192126434835527, -0.4713967368259972), (0.83146961230254557, -0.55557023301960173), (0.77301045336273744, -0.63439328416364493), (0.70710678118654813, -0.70710678118654691), (0.63439328416364626, -0.77301045336273633), (0.55557023301960307, -0.83146961230254468), (0.47139673682599859, -0.88192126434835449), (0.38268343236509084, -0.92387953251128629), (0.29028467725446361, -0.95694033573220849), (0.19509032201612964, -0.98078528040323021), (0.098017140329562089, -0.99518472667219671), (1.615542552166338e-15, -1.0), (-0.098017140329558883, -0.99518472667219704), (-0.19509032201612647, -0.98078528040323076), (-0.2902846772544605, -0.95694033573220938), (-0.38268343236508784, -0.92387953251128752), (-0.4713967368259957, -0.88192126434835605), (-0.55557023301960051, -0.83146961230254635), (-0.63439328416364393, -0.77301045336273821), (-0.70710678118654624, -0.70710678118654879), (-0.77301045336273588, -0.63439328416364682), (-0.83146961230254435, -0.55557023301960362), (-0.88192126434835427, -0.47139673682599903), (-0.92387953251128618, -0.38268343236509111), (-0.95694033573220849, -0.29028467725446366), (-0.98078528040323021, -0.19509032201612947), (-0.99518472667219682, -0.098017140329561714), (-1.0, -1.010639055082363e-15), (-0.99518472667219693, 0.098017140329559702), (-0.98078528040323065, 0.1950903220161275), (-0.95694033573220905, 0.29028467725446172), (-0.92387953251128696, 0.38268343236508923), (-0.88192126434835527, 0.47139673682599725), (-0.83146961230254546, 0.55557023301960196), (-0.7730104533627371, 0.63439328416364527), (-0.70710678118654768, 0.70710678118654746), (-0.63439328416364593, 0.77301045336273666), (-0.55557023301960295, 0.83146961230254479), (-0.4713967368259987, 0.88192126434835449), (-0.38268343236509117, 0.92387953251128618), (-0.29028467725446411, 0.95694033573220838), (-0.19509032201613041, 0.98078528040322999), (-0.098017140329563102, 0.9951847266721966), (-2.8482262121737323e-15, 1.0), (0.098017140329557426, 0.99518472667219715), (0.19509032201612481, 0.9807852804032311), (0.29028467725445867, 0.95694033573220993), (0.3826834323650859, 0.9238795325112884), (0.47139673682599365, 0.88192126434835716), (0.55557023301959818, 0.8314696123025479), (0.63439328416364149, 0.77301045336274021), (0.70710678118654358, 0.70710678118655146), (0.77301045336273322, 0.63439328416365004), (0.83146961230254179, 0.5555702330196074), (0.88192126434835194, 0.47139673682600342), (0.92387953251128407, 0.38268343236509617), (0.95694033573220671, 0.29028467725446927), (0.98078528040322899, 0.19509032201613569), (0.99518472667219615, 0.098017140329568472), (1.0, 8.2385270480656025e-15), (1.0, 0.0)]

Como puede ver, el círculo está compuesto por 65 puntos espaciados 0.0966 unidades el uno del otro.


10
2017-10-30 06:01



Para aquellos que están interesados, aquí hay un ejemplo para crear una elipse con una longitud de eje de 15 y 20.

from shapely.geometry.point import Point
import shapely.affinity

circle=Point(0,0).buffer(1) #type(circle)=polygon
ellipse=shapely.affinity.scale(circle,15,20) #type(ellipse)=polygon

5
2017-12-22 08:01