title: Set the y-axis to scale in a Seaborn heat map
body: <p>I currently have a dataframe, df:</p>
  <pre class="lang-none prettyprint-override"><code>In  [1]: df
  Out [1]:
  
     one        two
        1.5    11.22
          2    15.36
        2.5    11
        3.3    12.5
        3.5    14.78
          5    9
        6.2    26.14
  </code></pre>
  <p>I used this code to get a heat map:</p>
  <pre class="lang-none prettyprint-override"><code>In [2]:
  
  plt.figure(figsize=(30, 7))
  plt.title('Test')
  ax = sns.heatmap(data=df, annot=True,)
  plt.xlabel('Test')
  ax.invert_yaxis()
  
  value = 6
  index = np.abs(df.index - value).argmin()
  ax.axhline(index + .5, ls='--')
  print(index)
  
  Out [2]:
  </code></pre>
  <p><img src="https://i.stack.imgur.com/Ui8RF.png" alt="Out [2] Result" /></p>
  <p>I am looking for the y-axis, instead, to automatically scale and plot the df[2] values in their respective positions on the full axis. For example, there should be a clear empty space between 3.5 and 5.0 as there aren’t any values - I want the values in between on the y-axis with 0 value against them.</p>