title: Seaborn heatmap change size of colorbar
body: <p>With the following code I plot a seaborn heatmap together with a colorbar.
  I want to set the size of the colorbar equal to the size of the heatmap.
  How can I achieve this?</p>
  
  <p>I have tried to adress the colorbar using <code>fig.colorbar(heatmap)</code> but this returns the error:</p>
  
  <pre><code>AttributeError: 'AxesSubplot' object has no attribute 'autoscale_None'
  </code></pre>
  
  <p>Code:</p>
  
  <pre><code>fig,ax=plt.subplots(figsize=(30,60))
  
  cmap = plt.get_cmap('inferno',30)
  cmap.set_under('white')#Colour values less than vmin in white
  cmap.set_over('yellow')# colour valued larger than vmax in red 
  
  Crosstab=50000*np.random.randn(10,10)
  
  heatmap=sns.heatmap(Crosstab[::-1],cmap=cmap,annot=False,square=True,ax=ax,vmin=1,vmax=50000,linewidths=0.8,linecolor="grey")
  
  
  
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/dDISz.png" rel="noreferrer"><img src="https://i.stack.imgur.com/dDISz.png" alt="enter image description here"></a></p>