too many legend with array column data in matplotlib
<p>I try to plot simple rotation matrix result with list data. but My figure with result array have so many index as screen dump image. and the second plot is not exact with my attribute(line style, etc.) 
I guess that I do mistake array handling to plot but don't know what.
Any comments are welcome. Thanks in advance.</p>

<p><a href="https://i.stack.imgur.com/i9HAP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/i9HAP.png" alt="enter image description here"></a></p>

<p>My code is below. </p>

<pre><code>import numpy as np
import matplotlib.pyplot as plt

theta = np.radians(30)
c, s = np.cos(theta), np.sin(theta)
R = np.matrix('{} {}; {} {}'.format(c, -s, s, c))
x = [-9, -8, -7, -6, -5, -4, -3, -2, -1,0,1,2,3,4,5,6,7,8,9]
y = [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]

line_b = [x,y]

result_a = R*np.array(line_b)

fig=plt.figure()
ax1 = fig.add_subplot(111)
plt.plot(line_b[0],line_b[1], color="blue", linewidth=2.5, linestyle="-",    label='measured')
plt.plot(result_a[0], result_a[1], 'r*-', label='rotated')
ax1.set_ylim(-10,10)
ax1.set_xlim(-10,10)
plt.legend()

# axis center to move 0,0
ax1.spines['right'].set_color('none')
ax1.spines['top'].set_color('none')
ax1.xaxis.set_ticks_position('bottom')
ax1.spines['bottom'].set_position(('data',0))
ax1.yaxis.set_ticks_position('left')
ax1.spines['left'].set_position(('data',0))

plt.show()
</code></pre>