title: python pandas loc return empty dataframe
body: <p>I am trying to get the subset dataframe using the below code:</p>
  
  <pre><code>dprev = "eiffel tower"
  
  df.loc[df['place'] == dprev] -&gt; returns empty
  
  drandom = random.choice(df['place'].unique())
  
  df.loc[df['place'] == drandom] -&gt; returns the subset
  </code></pre>
  
  <p>why am i not seeing the same thing when <code>dprev</code> is string variable?</p>