title: Remove Empty DataFrame in pandas
body: <p>I've got this following dataframe that contains an empty row because the value missing for selected slot (which is a time):</p>
  <pre><code>    slot       tempo
  10  7--8  132.559556
     slot     tempo
  8  7--8  135.0565
     slot       tempo
  9  7--8  125.582778
     slot       tempo
  7  7--8  117.038667
     slot       tempo
  9  7--8  135.946333
  Empty DataFrame
  Columns: [slot, tempo]
  Index: []
     slot       tempo
  2  7--8  123.476571
     slot       tempo
  3  7--8  125.724286
     slot    tempo
  2  7--8  139.503
     slot       tempo
  2  7--8  140.977429
     slot       tempo
  1  7--8  135.035875
     slot       tempo
  1  7--8  120.741556
  </code></pre>
  <p>The code i used to obtain this df is:</p>
  <pre><code>path = os.getcwd()
  csv_files = glob.glob(os.path.join(path, &quot;*.csv&quot;))
  
  for f in csv_files:
      dfDay = pd.read_csv(f, encoding = &quot;ISO-8859-1&quot;, sep = ';')
      
      dfSlotMean = dfDay.groupby('slot', as_index=False)['tempo'].mean()
      
      slotMorningMean = dfSlotMean[dfSlotMean.slot == '7--8']
      # print(type(slotMorningMean))
      print((slotMorningMean))
  </code></pre>
  <p>How can i remove this empty dataframe? I already try dropna(how='all') but didn't work.</p>