title: How to launch a conditinated selection of dataframe's row with mixed values
body: <p>I am trying to use the conditioned selection of interested rows/columns into the followng dataset:</p>
  <pre><code>import pandas as pd
  
  already_read = [(&quot;Il nome della rosa&quot;,&quot;Umberto Eco&quot;, 1980), 
          (&quot;L'amore che ti meriti&quot;,&quot;Daria Bignardi&quot;, 2014), 
          (&quot;Memorie dal sottsuolo&quot;, &quot; Fëdor Dostoevskij&quot;, 1864), 
          (&quot;Oblomov&quot;, &quot;Ivan Alexandrovich Goncharov &quot;, '/')]
  
  index = range(1,5,1)
  data = pd.DataFrame(already_read, columns = [&quot;Books'Title&quot;, &quot;Authors&quot;, &quot;Publishing Year&quot;], index = index)
  data
  </code></pre>
  <p>In the following way:</p>
  <pre><code>data[(data['Publishing Year'] &gt;= 1850) &amp; (data['Publishing Year'] &lt;= 1950)]
  </code></pre>
  <p>As you could see, the column I have chosen contains mixed data <code>(int and str)</code> and indeed I have this error after running the code:</p>
  <pre><code>TypeError: '&gt;=' not supported between instances of 'str' and 'int'
  </code></pre>
  <p>If please, since I'm moving my very first step with Python, could you please suggest some way to run that code in a way that the string value is excluded or it is read as an integer, possibly by implementing <code>*if statement?*</code> (or another method)?</p>
  <p>Thanks</p>