title: Casting complex values to real discards the imaginary part
body: <pre><code>x = [[(1+2j) ,(2+8j), (4+1j), (6+8j), (7+3j), (8+2j)],
       [(3+8j), (5+1j), (7+5j), (3+2j), (6+1j), (3+1j)],
       [(1+5j), (5+4j), (2+9j), (9+5j), (8+1j), (4+1j)]]
  </code></pre>
  <p>I have a complex numpy array and I want to plot it with matplotlib.</p>
  <pre><code>t = np.linspace(0, 2700, 2700)
  plt.plot(t,x[0])
  plt.xlabel('Range')
  plt.ylabel('I+jQ')
  plt.xlim([0, 2700])
  plt.show()
  </code></pre>
  <p>When I run this code I get a failure like this:</p>
  <pre><code>/home/user/.local/lib/python3.8/site-packages/numpy/core/_asarray.py:102: ComplexWarning: Casting complex values to real discards the imaginary part
    return array(a, dtype, copy=False, order=order)
  </code></pre>
  <p>I mean when I run this code I get a plot but this code draw only real part.</p>