title: Create Seaborn Heatmap on one column in a df
body: <p>Afternoon All,</p>
  <p>I'm looking to create a heatmap of one column in my df. So <code>inc_Year_Month</code> on y axis and <code>Count</code> on the x axis</p>
  <pre><code>import matplotlib.pyplot as plt
  from matplotlib.colors import ListedColormap
  
  data = {
  'inc_Year_Month':['2020-07','2020-08','2020-09','2020-10','2020-11','2020-12','2021-01','2021-02','2021-03','2021-04'],
  'Count':[2,4,6,8,10,12,30,50,60,100],
  }
  dfTemp = pd.DataFrame(dict(data))
  print(dfTemp)
  
  dfTemp2 = np.asarray(dfTemp).reshape(dfTemp.shape[0],1)
  df_heatmap = sns.heatmap(dfTemp2, annot=True, fmt=&quot;g&quot;, cmap='magma')
  # df_heatmap = sns.heatmap(dfTemp2,cmap=ListedColormap(['green', 'yellow', 'red']))
  df_heatmap_Figure = df_heatmap.get_figure()
  # # Set to high resolution and save
  df_heatmap_Figure.savefig('Hi Res Seaborn-heatmap2.png', dpi=300) 
  </code></pre>
  <p>I get the error:</p>
  <pre><code>ValueError: cannot reshape array of size 20 into shape (10,1)
  </code></pre>
  <p>I thought I could resolve this by forcing the rectangular 2D dataset into an ndarray:</p>
  <pre><code>dfTemp2 = np.asarray(dfTemp).reshape(dfTemp.shape[0],1)
  </code></pre>