title: make single plot from multi columns in matplotlib subplots
body: <p>I'm using quite often matplotlibs subplots and i want something like this:</p>
  <pre><code>import mumpy as np
  import matplotlib.pyplot as plt
  
  fig, ax = plt.subplots(3, 2, figsize=(8, 10), sharey='row',
                         gridspec_kw={'height_ratios': [1, 2, 2]})
  ax[0, :].plot(np.random.randn(128))
  
  ax[1, 0].plot(np.arange(128))
  ax[1, 1].plot(1 / (np.arange(128) + 1))
  
  ax[2, 0].plot(np.arange(128) ** (2))
  ax[2, 1].plot(np.abs(np.arange(-64, 64)))
  </code></pre>
  <p>I want to create a figure that have for 2 positions a single plot like done for <code>ax1</code> in this (modified) gridspec example:</p>
  <pre><code>import matplotlib.pyplot as plt
  from matplotlib.gridspec import GridSpec
  
  fig = plt.figure()
  
  gs = GridSpec(3, 3)
  ax1 = plt.subplot(gs[0, :])
  # identical to ax1 = plt.subplot(gs.new_subplotspec((0, 0), colspan=3))
  ax2 = plt.subplot(gs[1, :-1])
  ax3 = plt.subplot(gs[1:, -1])
  ax4 = plt.subplot(gs[-1, 0])
  ax5 = plt.subplot(gs[-1, -2])
  
  fig.suptitle(&quot;GridSpec&quot;)
  
  plt.show()
  </code></pre>
  <p>see for full example: <a href="https://matplotlib.org/gallery/userdemo/demo_gridspec02.html#sphx-glr-gallery-userdemo-demo-gridspec02-py" rel="nofollow noreferrer">https://matplotlib.org/gallery/userdemo/demo_gridspec02.html#sphx-glr-gallery-userdemo-demo-gridspec02-py</a></p>
  <p>Since i'm using the subplots environment quite a lot i would know if this is possible too. Also because subplots can handle GridSpec arguments. The pity is that it is not really explained what the exceptions are.</p>