""" Compare the ellipse generated with arcs versus a polygonal approximation """ from basic_units import cm import numpy as npy from matplotlib import patches from pylab import figure, show xcenter, ycenter = 0.38*cm, 0.52*cm #xcenter, ycenter = 0., 0. width, height = 1e-1*cm, 3e-1*cm angle = -30 theta = npy.arange(0.0, 360.0, 1.0)*npy.pi/180.0 x = 0.5 * width * npy.cos(theta) y = 0.5 * height * npy.sin(theta) rtheta = angle*npy.pi/180. R = npy.array([ [npy.cos(rtheta), -npy.sin(rtheta)], [npy.sin(rtheta), npy.cos(rtheta)], ]) x, y = npy.dot(R, npy.array([x, y])) x += xcenter y += ycenter fig = figure() ax = fig.add_subplot(211, aspect='auto') ax.fill(x, y, alpha=0.2, facecolor='yellow', edgecolor='yellow', linewidth=1, zorder=1) e1 = patches.Ellipse((xcenter, ycenter), width, height, angle=angle, linewidth=2, fill=False, zorder=2) ax.add_patch(e1) ax = fig.add_subplot(212, aspect='equal') ax.fill(x, y, alpha=0.2, facecolor='green', edgecolor='green', zorder=1) e2 = patches.Ellipse((xcenter, ycenter), width, height, angle=angle, linewidth=2, fill=False, zorder=2) ax.add_patch(e2) #fig.savefig('ellipse_compare.png') fig.savefig('ellipse_compare') fig = figure() ax = fig.add_subplot(211, aspect='auto') ax.fill(x, y, alpha=0.2, facecolor='yellow', edgecolor='yellow', linewidth=1, zorder=1) e1 = patches.Arc((xcenter, ycenter), width, height, angle=angle, linewidth=2, fill=False, zorder=2) ax.add_patch(e1) ax = fig.add_subplot(212, aspect='equal') ax.fill(x, y, alpha=0.2, facecolor='green', edgecolor='green', zorder=1) e2 = patches.Arc((xcenter, ycenter), width, height, angle=angle, linewidth=2, fill=False, zorder=2) ax.add_patch(e2) #fig.savefig('arc_compare.png') fig.savefig('arc_compare') show()