title: Gridspec inside Gridspec
body: <p>I want to creat a GridSpec inside a Gridpec.
  I can already create some GridSpecs like my Code here:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  
  for i in range(40):
      i = i + 1
      ax1 = plt.subplot(10, 4, i)
      plt.axis('on')
      ax1.set_xticklabels([])
      ax1.set_yticklabels([])
      ax1.set_aspect('equal')
      plt.subplots_adjust(wspace=None, hspace=None)
  plt.show()
  </code></pre>
  
  <p>But I want 40 gridspecs. 
  In Every Gridspec should be another 21 Grids (inner_grid)
  and in every inner_grid should be one grid on the top and 6 grids in a row should fill the rest.
  Nearly like the picture in the end of this link:
  <a href="https://matplotlib.org/tutorials/intermediate/gridspec.html" rel="nofollow noreferrer">https://matplotlib.org/tutorials/intermediate/gridspec.html</a>
  But I don't really understand it.</p>
  
  <p>I have tried this:</p>
  
  <pre><code>import matplotlib as mpl
  from matplotlib.gridspec import GridSpec
  import matplotlib.gridspec as gridspec
  import matplotlib.pyplot as plt
  
      fig = plt.figure(figsize=(5,10), dpi=300)
      ax = plt.subplot(gs[i])
      #trying to make multiple gridspec
      # gridspec inside gridspec
          outer_grid = gridspec.GridSpec(48, 1, wspace=0.0, hspace=0.0)
  
          for i in range(21):
              #ax = plt.subplot(5, 5, i)
              inner_grid = gridspec.GridSpecFromSubplotSpec(5, 5, subplot_spec=outer_grid[i], wspace=0.0, hspace=0.0)
              a, b = int(i/4)+1, i % 4+1
              for j in enumerate(product(range(1, 4), repeat=2)):
                  ax = plt.Subplot(fig, inner_grid[j])
                  ax.set_xticks([])
                  ax.set_yticks([])
                  fig.add_subplot(ax)
  
      all_axes = fig.get_axes()
  </code></pre>