title: How can I get a value from a cell of a dataframe?
body: <p>I have constructed a condition that extracts exactly one row from my data frame:</p>
  <pre><code>d2 = df[(df['l_ext']==l_ext) &amp; (df['item']==item) &amp; (df['wn']==wn) &amp; (df['wd']==1)]
  </code></pre>
  <p>Now I would like to take a value from a particular column:</p>
  <pre><code>val = d2['col_name']
  </code></pre>
  <p>But as a result, I get a data frame that contains one row and one column (i.e., one cell). It is not what I need. I need one value (one float number). How can I do it in pandas?</p>