擅长:python、mysql、java
<p>这里不使用散点是有意义的,因为这需要计算散点在数据单位中的点数。用圆圈代替是可以的。在</p>
<p>箭头被放置在根据月球轨道<code>R_avg</code>的位置。它们的长度在这里是任意的,但是你当然可以随意改变它。在</p>
<pre><code>import matplotlib.pyplot as plt
R_min=356.5e6 #Perigee
R_max=406.7e6 #Apogee
R_avg = 0.5*(R_min + R_max)
r = 6.3781e6 #radius of Earth
ax = plt.gca()
ax.set_aspect("equal")
i = 0
# create arrows on moon orbit, both one orbit radius in length to both directions
ax.quiver([0,0], [R_avg,R_avg], [1,0], [0, 1], angles='xy',
scale_units='xy', scale=1./R_avg)
# create earth and moon orbit
earth = plt.Circle((0,0),r)
orbit = plt.Circle((0,0),R_avg, fill=False, color="crimson")
ax.add_patch(earth)
ax.add_patch(orbit)
ax.autoscale_view()
ax.margins(1)
plt.show()
</code></pre>
<p><a href="https://i.stack.imgur.com/qJmwj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qJmwj.png" alt="enter image description here"/></a></p>