Polygons

class sage.plot.polygon.Polygon(xdata, ydata, options)

Bases: sage.plot.primitive.GraphicPrimitive_xydata

Primitive class for the Polygon graphics type. For information on actual plotting, please see polygon(), polygon2d(), or polygon3d().

INPUT:

  • xdata - list of \(x\)-coordinates of points defining Polygon
  • ydata - list of \(y\)-coordinates of points defining Polygon
  • options - dict of valid plot options to pass to constructor

EXAMPLES:

Note this should normally be used indirectly via polygon():

sage: from sage.plot.polygon import Polygon
sage: P = Polygon([1,2,3],[2,3,2],{'alpha':.5})
sage: P
Polygon defined by 3 points
sage: P.options()['alpha']
0.500000000000000
sage: P.ydata
[2, 3, 2]

TESTS:

We test creating polygons:

sage: polygon([(0,0), (1,1), (0,1)])
sage: polygon([(0,0,1), (1,1,1), (2,0,1)])
plot3d(z=0, **kwds)

Plots a 2D polygon in 3D, with default height zero.

INPUT:

  • z - optional 3D height above \(xy\)-plane, or a list of heights corresponding to the list of 2D polygon points.

EXAMPLES:

A pentagon:

sage: polygon([(cos(t), sin(t)) for t in srange(0, 2*pi, 2*pi/5)]).plot3d()

Showing behavior of the optional parameter z:

sage: P = polygon([(0,0), (1,2), (0,1), (-1,2)])
sage: p = P[0]; p
Polygon defined by 4 points
sage: q = p.plot3d()
sage: q.obj_repr(q.testing_render_params())[2]
['v 0 0 0', 'v 1 2 0', 'v 0 1 0', 'v -1 2 0']
sage: r = p.plot3d(z=3)
sage: r.obj_repr(r.testing_render_params())[2]
['v 0 0 3', 'v 1 2 3', 'v 0 1 3', 'v -1 2 3']
sage: s = p.plot3d(z=[0,1,2,3])
sage: s.obj_repr(s.testing_render_params())[2]
['v 0 0 0', 'v 1 2 1', 'v 0 1 2', 'v -1 2 3']

TESTS:

Heights passed as a list should have same length as number of points:

sage: P = polygon([(0,0), (1,2), (0,1), (-1,2)])
sage: p = P[0]
sage: q = p.plot3d(z=[2,-2])
Traceback (most recent call last):
...
ValueError: Incorrect number of heights given
sage.plot.polygon.polygon(points, **options)

Returns either a 2-dimensional or 3-dimensional polygon depending on value of points.

For information regarding additional arguments, see either polygon2d() or polygon3d(). Options may be found and set using the dictionaries polygon2d.options and polygon3d.options.

EXAMPLES:

sage: polygon([(0,0), (1,1), (0,1)])
sage: polygon([(0,0,1), (1,1,1), (2,0,1)])

Extra options will get passed on to show(), as long as they are valid:

sage: polygon([(0,0), (1,1), (0,1)], axes=False)
sage: polygon([(0,0), (1,1), (0,1)]).show(axes=False) # These are equivalent
sage.plot.polygon.polygon2d(points, legend_color=None, rgbcolor=(0, 0, 1), thickness=None, aspect_ratio=1.0, alpha=1, legend_label=None, fill=True, **options)

Returns a 2-dimensional polygon defined by points.

Type polygon2d.options for a dictionary of the default options for polygons. You can change this to change the defaults for all future polygons. Use polygon2d.reset() to reset to the default options.

EXAMPLES:

We create a purple-ish polygon:

sage: polygon2d([[1,2], [5,6], [5,0]], rgbcolor=(1,0,1))

By default, polygons are filled in, but we can make them without a fill as well:

sage: polygon2d([[1,2], [5,6], [5,0]], fill=False)

In either case, the thickness of the border can be controlled:

sage: polygon2d([[1,2], [5,6], [5,0]], fill=False, thickness=4, color='orange')

Some modern art – a random polygon, with legend:

sage: v = [(randrange(-5,5), randrange(-5,5)) for _ in range(10)]
sage: polygon2d(v, legend_label='some form')

A purple hexagon:

sage: L = [[cos(pi*i/3),sin(pi*i/3)] for i in range(6)]
sage: polygon2d(L, rgbcolor=(1,0,1))

A green deltoid:

sage: L = [[-1+cos(pi*i/100)*(1+cos(pi*i/100)),2*sin(pi*i/100)*(1-cos(pi*i/100))] for i in range(200)]
sage: polygon2d(L, rgbcolor=(1/8,3/4,1/2))

A blue hypotrochoid:

sage: L = [[6*cos(pi*i/100)+5*cos((6/2)*pi*i/100),6*sin(pi*i/100)-5*sin((6/2)*pi*i/100)] for i in range(200)]
sage: polygon2d(L, rgbcolor=(1/8,1/4,1/2))

Another one:

sage: n = 4; h = 5; b = 2
sage: L = [[n*cos(pi*i/100)+h*cos((n/b)*pi*i/100),n*sin(pi*i/100)-h*sin((n/b)*pi*i/100)] for i in range(200)]
sage: polygon2d(L, rgbcolor=(1/8,1/4,3/4))

A purple epicycloid:

sage: m = 9; b = 1
sage: L = [[m*cos(pi*i/100)+b*cos((m/b)*pi*i/100),m*sin(pi*i/100)-b*sin((m/b)*pi*i/100)] for i in range(200)]
sage: polygon2d(L, rgbcolor=(7/8,1/4,3/4))

A brown astroid:

sage: L = [[cos(pi*i/100)^3,sin(pi*i/100)^3] for i in range(200)]
sage: polygon2d(L, rgbcolor=(3/4,1/4,1/4))

And, my favorite, a greenish blob:

sage: L = [[cos(pi*i/100)*(1+cos(pi*i/50)), sin(pi*i/100)*(1+sin(pi*i/50))] for i in range(200)]
sage: polygon2d(L, rgbcolor=(1/8, 3/4, 1/2))

This one is for my wife:

sage: L = [[sin(pi*i/100)+sin(pi*i/50),-(1+cos(pi*i/100)+cos(pi*i/50))] for i in range(-100,100)]
sage: polygon2d(L, rgbcolor=(1,1/4,1/2))

One can do the same one with a colored legend label:

sage: polygon2d(L, color='red', legend_label='For you!', legend_color='red')

Polygons have a default aspect ratio of 1.0:

sage: polygon2d([[1,2], [5,6], [5,0]]).aspect_ratio()
1.0

AUTHORS:

  • David Joyner (2006-04-14): the long list of examples above.

Previous topic

Points

Next topic

Plotting primitives

This Page