+++ /dev/null
-LinPy Examples
-==============
-
-Basic Examples
--------------
- To create any polyhedron, first define the symbols used. Then use the polyhedron functions to define the constraints. The following is a simple running example illustrating some different operations and properties that can be performed by LinPy with two squares.
-
- >>> from linpy import *
- >>> x, y = symbols('x y')
- >>> # define the constraints of the polyhedron
- >>> square1 = Le(0, x) & Le(x, 2) & Le(0, y) & Le(y, 2)
- >>> square1
- And(Ge(x, 0), Ge(-x + 2, 0), Ge(y, 0), Ge(-y + 2, 0))
-
- Binary operations and properties examples:
-
- >>> square2 = Le(1, x) & Le(x, 3) & Le(1, y) & Le(y, 3)
- >>> #test equality
- >>> square1 == square2
- False
- >>> # compute the union of two polyhedrons
- >>> square1 | square2
- Or(And(Ge(x, 0), Ge(-x + 2, 0), Ge(y, 0), Ge(-y + 2, 0)), And(Ge(x - 1, 0), Ge(-x + 3, 0), Ge(y - 1, 0), Ge(-y + 3, 0)))
- >>> # check if square1 and square2 are disjoint
- >>> square1.disjoint(square2)
- False
- >>> # compute the intersection of two polyhedrons
- >>> square1 & square2
- And(Ge(x - 1, 0), Ge(-x + 2, 0), Ge(y - 1, 0), Ge(-y + 2, 0))
- >>> # compute the convex union of two polyhedrons
- >>> Polyhedron(square1 | sqaure2)
- And(Ge(x, 0), Ge(y, 0), Ge(-y + 3, 0), Ge(-x + 3, 0), Ge(x - y + 2, 0), Ge(-x + y + 2, 0))
-
- Unary operation and properties examples:
-
- >>> square1.isempty()
- False
- >>> square1.symbols()
- (x, y)
- >>> square1.inequalities
- (x, -x + 2, y, -y + 2)
- >>> # project out the variable x
- >>> square1.project([x])
- And(Ge(-y + 2, 0), Ge(y, 0))
-
-Plot Examples
--------------
-
- LinPy uses matplotlib plotting library to plot 2D and 3D polygons. The user has the option to pass subplots to the :meth:`plot` method. This can be a useful tool to compare polygons. Also, key word arguments can be passed such as color and the degree of transparency of a polygon.
-
- >>> import matplotlib.pyplot as plt
- >>> from matplotlib import pylab
- >>> from mpl_toolkits.mplot3d import Axes3D
- >>> from linpy import *
- >>> # define the symbols
- >>> x, y, z = symbols('x y z')
- >>> fig = plt.figure()
- >>> cham_plot = fig.add_subplot(1, 1, 1, projection='3d', aspect='equal')
- >>> cham_plot.set_title('Chamfered cube')
- >>> cham = Le(0, x) & Le(x, 3) & Le(0, y) & Le(y, 3) & Le(0, z) & \
- Le(z, 3) & Le(z - 2, x) & Le(x, z + 2) & Le(1 - z, x) & \
- Le(x, 5 - z) & Le(z - 2, y) & Le(y, z + 2) & Le(1 - z, y) & \
- Le(y, 5 - z) & Le(y - 2, x) & Le(x, y + 2) & Le(1 - y, x) & Le(x, 5 - y)
- >>> cham.plot(cham_plot, facecolor='red', alpha=0.75)
- >>> pylab.show()
-
- .. figure:: images/cham_cube.jpg
- :align: center
-
-LinPy can also inspect a polygon's vertices and the integer points included in the polygon.
-
- >>> diamond = Ge(y, x - 1) & Le(y, x + 1) & Ge(y, -x - 1) & Le(y, -x + 1)
- >>> diamond.vertices()
- [Point({x: Fraction(0, 1), y: Fraction(1, 1)}), \
- Point({x: Fraction(-1, 1), y: Fraction(0, 1)}), \
- Point({x: Fraction(1, 1), y: Fraction(0, 1)}), \
- Point({x: Fraction(0, 1), y: Fraction(-1, 1)})]
- >>> diamond.points()
- [Point({x: -1, y: 0}), Point({x: 0, y: -1}), Point({x: 0, y: 0}), \
- Point({x: 0, y: 1}), Point({x: 1, y: 0})]
-
-The user also can pass another plot to the :meth:`plot` method. This can be useful to compare two polyhedrons on the same axis. This example illustrates the union of two squares.
-
- >>> from linpy import *
- >>> import matplotlib.pyplot as plt
- >>> from matplotlib import pylab
- >>> x, y = symbols('x y')
- >>> square1 = Le(0, x) & Le(x, 2) & Le(0, y) & Le(y, 2)
- >>> square2 = Le(1, x) & Le(x, 3) & Le(1, y) & Le(y, 3)
- >>> fig = plt.figure()
- >>> plot = fig.add_subplot(1, 1, 1, aspect='equal')
- >>> square1.plot(plot, facecolor='red', alpha=0.3)
- >>> square2.plot(plot, facecolor='blue', alpha=0.3)
- >>> squares = Polyhedron(square1 + square2)
- >>> squares.plot(plot, facecolor='blue', alpha=0.3)
- >>> pylab.show()
-
- .. figure:: images/union.jpg
- :align: center
-
-
-
-