title: Filter out non-numeric values from column
body: <p>I have the following column in pandas DataFrame:</p>
  
  <pre><code>col1
  1.2
  1.4
  3.1
  aa
  bb
  NaN
  </code></pre>
  
  <p>I need to calculate the minimum value in the column <code>col1</code> while ignoring all empty and non-numeric values.</p>
  
  <p>If I do <code>df[col1].min()</code>, it only ignores empty values, but I still get this error:</p>
  
  <pre><code>TypeError: '&lt;=' not supported between instances of 'float' and 'str'
  </code></pre>