Python Sympy Polygon.cut_section()用法及代码示例

在Sympy中，函数Polygon.cut_section()用于获取分别位于相交线上方和下方的两个多边形段(多边形的two-part)的元组。它仅返回由线相交的多边形的两个部分。当线上方或线下方不存在多边形时，返回None。

用法：Polygon.cut_section(line)

返回： upper_polygon, lower_polygon:Polygon objects or None
 upper_polygon:is the polygon that lies above the given line
 lower_polygon: is the polygon that lies below the given line
 None: when no polygon exists above the line or below the line
 
Raises:
 ValueError: When the line does not intersect the polygon

范例1：

# import sympy import Point, Polygon, Line 
from sympy import Point, Polygon, Line 
  
# creating points using Point() 
p1, p2, p3, p4 = map(Point, [(0, 2), (0, 0), (1, 0), (1, 2)]) 
  
# creating polygon using Polygon() 
poly = Polygon(p1, p2, p3, p4) 
  
# using cut_section() 
cutSection = poly.cut_section(Line((0, 1), slope = 0)) 
  
print(cutSection)

输出：

(Polygon(Point2D(0, 2), Point2D(0, 1), Point2D(1, 1), Point2D(1, 2)), 
 Polygon(Point2D(0, 1), Point2D(0, 0), Point2D(1, 0), Point2D(1, 1)))

范例2：

# import sympy import Point, Polygon, Line 
from sympy import Point, Polygon, Line 
  
# creating points using Point() 
p1, p2, p3, p4 = map(Point, [(0, 2), (0, 0), (1, 0), (1, 2)]) 
  
# creating polygon using Polygon() 
poly = Polygon(p1, p2, p3, p4) 
  
# using cut_section() 
cutSection = poly.cut_section(Line((0, 1), slope = 1)) 
  
print(cutSection)

输出：

(Triangle(Point2D(0, 2), Point2D(0, 1), Point2D(1, 2)), 
 Polygon(Point2D(0, 1), Point2D(0, 0), Point2D(1, 0), Point2D(1, 2)))