matplotlibでポリゴンをプロットする、頂点でエラーが発生する

Question

x^11 + 1 = 0のポリゴンをプロットしようとしていますが、マトリックスの寸法に誤差があります。行列要素はポリゴンの頂点です。コード：

import numpy as np 
import matplotlib.pyplot as plt 
from matplotlib.collections import PolyCollection 


n = 11 
verticesx = np.empty(shape=0) 
for k in np.arange(n): 
    verticesx = np.append(verticesx, [[np.cos(np.rad2deg((2 * k + 1)/n * np.pi))], 
             [np.sin(np.rad2deg((2 * k + 1)/n * np.pi))]]) 
print(verticesx) 
plt.subplot(aspect='equal') 
plt.xlim(-1.5, 1.5) 
plt.ylim(-1.5, 1.5) 
circle = plt.Circle((0, 0), 1, color='b', fill=False) 
poly = PolyCollection(verticesx, facecolor='r', edgecolor='g', closed=True) 
plt.gcf().gca().add_artist(circle) 
plt.gcf().gca().add_artist(poly) 

エラーメッセージはこの1つである：

[-0.79263773 -0.6096929 0.38593669 -0.92252527 0.99066117 
0.13634679 
    0.12236983 0.99248457 -0.92787342 0.37289531 -0.59846007 -0.80115264 
    0.6208046 -0.78396533 0.91699383 0.39890139 -0.15029666 0.98864094  -0.99411079 0.10836856 -0.35977985 -0.93303722] 
Traceback (most recent call last): File 
"F:/MISCOSAS/ProgramasPython3/Circunferencia/circunferenciaunidad.py", 
line 15, in <module> 
    poly = PolyCollection(verticesx, facecolor='r', edgecolor='g', closed=True) File 
"C:\Anaconda3\lib\site-packages\matplotlib\collections.py", line 867, 
in __init__ 
    self.set_verts(verts, closed) File "C:\Anaconda3\lib\site-packages\matplotlib\collections.py", line 878, 
in set_verts 
    if len(xy): TypeError: object of type 'numpy.float64' has no len() 

Process finished with exit code 1 

Answer 1

import numpy as np 
from __future__ import division 
import matplotlib.pyplot as plt 
from matplotlib.collections import PolyCollection 


n = 11 
verts = [] 

k=np.linspace(0,n,1.0) 

for k in range(n): 
    a=360/11/180*np.pi 
    x= np.cos(k*a) 
    y= np.sin(k*a) 
    verts.append((x,y)) 
    # appending to a numpy array works differently than appending to a list 


plt.subplot(aspect='equal') 
# plt.xlim(-1.5, 1.5) 
# plt.ylim(-1.5, 1.5) 
circle = plt.Circle((0, 0), 1, color='b', fill=False) 

# you need to pass a collection here, not just one polygon, solve that by putting brackets around 
poly = PolyCollection([verts], facecolor='r', edgecolor='g', closed=True) 


plt.gcf().gca().add_artist(circle) 
plt.gcf().gca().add_artist(poly) 
plt.xlim(-1, 1) 
plt.ylim(-1, 1) 
plt.show()