title: iterate of df colomns to give rows with text
body: <p>I have a dataframe with columns. The columns have mostly blank rows but a few of the rows have strings and those are the only rows i want to see. I have tried the below code but dont know how to only select strings in the columns and append to get a new dataframe with only columns with strings in the rows.</p>
  
  <pre><code>columns = list(df) 
  
  for i in columns: 
  
      df1 = df[df[i]== ] 
  </code></pre>
  
  <p>can someone please help?</p>