title: ZeroDivisionError while trying to plot corelation matrix
body: <p>I am trying to plot the corelation matrix from pandas dataframe</p>
  
  <pre><code>import matplotlib.pyplot as plt
  import pandas as pd
  
  data = pd.read_csv('data_for_corelation.csv', delimiter=';')
  df = pd.DataFrame(data,columns=['A','B'])
  plt.matshow(df.corr())
  plt.show()
  </code></pre>
  
  <p>But I am getting an error at this line:</p>
  
  <pre><code>plt.matshow(df.corr())
  </code></pre>
  
  <p>And error is: </p>
  
  <pre><code>/usr/local/lib/python3.6/dist-packages/matplotlib/figure.py in figaspect(arg)
     2759     if isarray:
     2760         nr, nc = arg.shape[:2]
  -&gt; 2761         arr_ratio = nr / nc
     2762     else:
     2763         arr_ratio = arg
  
  ZeroDivisionError: division by zero
  </code></pre>
  
  <p>Sample data:</p>
  
  <pre><code>print(df.head(10))
  
         A           B
  0  249,640704  1,019356
  1  242,324502  0,647166
  2  243,495232  0,644257
  3  243,310156   0,81684
  4  243,511297  1,050207
  5  239,435233  1,340164
  6  240,091439  1,836193
  7   241,08975  1,540461
  8  237,017175  1,244953
  9  236,141326  1,210147
  </code></pre>
  
  <p>How should I fix it? </p>