title: Compare two columns using pandas
body: <p>Using this as a starting point:</p>
  
  <pre><code>a = [['10', '1.2', '4.2'], ['15', '70', '0.03'], ['8', '5', '0']]
  df = pd.DataFrame(a, columns=['one', 'two', 'three'])
  
  Out[8]: 
    one  two three
  0   10  1.2   4.2
  1   15  70   0.03
  2    8   5     0
  </code></pre>
  
  <p>I want to use something like an <code>if</code> statement within pandas. </p>
  
  <pre><code>if df['one'] &gt;= df['two'] and df['one'] &lt;= df['three']:
      df['que'] = df['one']
  </code></pre>
  
  <p>Basically, check each row via the <code>if</code> statement, create new column. </p>
  
  <p>The docs say to use <code>.all</code> but there is no example...</p>