I want to plot perpendicular vectors in Python
<p>I would like to simply plot perpendicular vectors in 2D. I've implemented 2 ways to plot them in the code below but the vectors don't "look" perpendicular to me when the plots are drawn. If it makes any difference I'm using Spyder.</p>

<pre><code>import numpy as np
import matplotlib.pyplot as plt
x1=[0,0,4,3]
x2=[0,0,-3,4]
x3=[0,0,3,-4]
soa =np.array([x1,x2,x3]) 
X,Y,U,V = zip(*soa) 
plt.figure()
ax = plt.gca()
ax.quiver(X,Y,U,V,angles='xy',scale_units='xy',scale=1)
ax.set_xlim([-10,10])
ax.set_ylim([-10,10])
plt.draw()
plt.show()

import pylab as pl
from matplotlib import collections  as mc
lines = [[(0, 1), (4, 3)], [(-3, 4), (3, -4)]]
c = np.array([(1, 0, 0, 1), (0, 1, 0, 1), (0, 0, 1, 1)])
lc = mc.LineCollection(lines, colors=c, linewidths=2)
fig, ax = pl.subplots()
ax.add_collection(lc)
ax.autoscale()
ax.margins(0.1)
</code></pre>