title: applying multiple conditions in pandas dataframe
body: <p>I want to fill an column with true or false, depending on whether a condition is met.
  I know to use any() method, but I need to compare values of two columns. I tried and have not succeeded- using &amp; gives type error.</p>
  <p>my data looks something like</p>
  <pre><code>A   B   condition_met
  1   2   
  3   3
  5   9
  7   2
  </code></pre>
  <p>the expected output is something like
  my data looks something like</p>
  <pre><code>A   B   condition_met
  1   2   true
  3   3   true
  5   9   true
  7   2   false
  </code></pre>
  <p>I want the value in condition_met if A&gt;3 and B&gt;4</p>
  <p>What I tried was</p>
  <pre><code>df.loc[df['A'] &gt; 3 &amp; 'B' &gt; 4, 'condition_met'] = 'True'
  </code></pre>
  <p>upd: I need to check if condition is met. i.e., if A&gt;3 then B&gt;4.
  if A&lt;=3 then it must still be true, since the condition doesn't exist.</p>