简单实现python画圆功能

import numpy as np import matplotlib.pyplot as plt from matplotlib.patches import Polygon import matplotlib.patches as mpatches  fig = plt.figure(figsize = (16,8)) ax = fig.gca() ax.set_xlim(-5,18) ax.set_ylim(-5,8) alpha = np.linspace(-np.pi,np.pi,30)  t = np.linspace(-np.pi,np.pi,100) def ppp(nc , na , c , sx , sy):  beta = alpha[na]  gam = alpha[na+1]  x = [] ; y = [] ;  r = 0.5*nc  x.append(r*np.cos(beta)) ; y.append(r*np.sin(beta)) ;  tt = np.linspace(beta,gam,10)  for i in range(len(tt)):   x.append(r*np.cos(tt[i]))   y.append(r*np.sin(tt[i]))  r-=0.5  x.append(r*np.cos(gam)) ; y.append(r*np.sin(gam))  tt = np.linspace(gam,beta,10)  for i in range(len(tt)):   x.append(r*np.cos(tt[i])) ; y.append(r*np.sin(tt[i]))  x = np.array(x) ; y = np.array(y)  verts = list(zip(x+sx,y+sy))  poly = Polygon(verts , facecolor=c , edgecolor=c)  ax.add_patch(poly)  #ppp(2,0,'r',0,0) def get_coordiate(x , y):  beta = (alpha[y]+alpha[y+1])/2  pr = 0.5*(x+x-1)/2  sx = pr*np.cos(beta) ; sy = pr*np.sin(beta)  return sx,sy def pp_arrow(x,y):  print x , y  sx , sy = get_coordiate(x, y)  for i in range(-1,2):   for j in range(-1,2):    if i == 0 and j == 0:     continue    ex , ey = get_coordiate(x+i, y+j)    ax.arrow(sx,sy,ex-sx,ey-sy,head_width=0.05,head_length=0.1,fc='r',ec='r')     def pxy(cx,cy):  for i in range(10):   plt.plot(0.5*i*np.cos(t)+cx,0.5*i*np.sin(t)+cy)   for i in range(len(alpha)):   plt.plot((0.5*np.cos(alpha)+cx,4.5*np.cos(alpha)+cx),(0.5*np.sin(alpha)+cy,4.5*np.sin(alpha)+cy))  cx = 13 ; cy =0 pxy(0,0) pxy(13,0)  mr = np.zeros((10,30)) mb = np.zeros((10,30))  for i in range(3,9):  for j in range(1,27):   ttt = np.random.random()   if ttt >= 0.98 and ttt <= 1:    ppp(i,j,'r',0,0)    mr[i][j] = 1    continue   if ttt < 0.8:    continue   else:    ppp(i,j,'b',0,0)    mb[i][j] = 1  for i in range(10):  for j in range(30):   if mr[i][j] == 0:    continue   pp_arrow(i, j)   ma = 0 ;posx = 1 ; posy = 1   for k in range(-1,2):    for s in range(-1,2):     mb[i+k][j+s]=0     ttt = np.random.random()     if ttt > ma:      ma = ttt      posx = k ; posy = s   ppp(i+posx , j+posy , 'r' , 13 , 0)   ppp(i,j,'g',13,0)  for i in range(10):  for j in range(30):   if mb[i][j] == 0:    continue   ppp(i , j , 'b' , 13 , 0)  arrow = mpatches.Arrow(5, 0       ,3,0,width = 1,color = 'r') ax.add_patch(arrow) ax.text(6.2,0.5,'after one/nunit time',ha='center',va='center',color='y')  xx = [4,4,4] yy = [7.5,6.5,5.5] c = ['b' , 'r' , 'g'] s = ['debris','satellite' , 'the location of satellite one unit time ago'] for i in range(3):  print xx[i] , yy[i]  rect = mpatches.Rectangle((xx[i],yy[i]),0.5,0.3,ec = c[i],fc=c[i] )  ax.text(xx[i]+0.7,yy[i],s[i])  ax.add_patch(rect) plt.axis('off') plt.show()