title: pandas: remove rows with missing data
body: <p>I am using the following code to remove some rows with missing data in pandas:</p>
  
  <pre><code>df = df.replace(r'^\s+$', np.nan, regex=True)
  df = df.replace(r'^\t+$', np.nan, regex=True)
  df = df.dropna()
  </code></pre>
  
  <p>However, I still have some cells in the data frame looks blank/empty. Why is this happening? Any way to get rid of rows with such empty/blank cells? Thanks!</p>