title: Remove rows from column on whitespaces
body: <p>I want to keep all the rows in column, which has single word and rest of the rows which contains more than one white space to be removed.</p>
  
  <p>My dataframe df is:</p>
  
  <pre><code>df['drug']
  gilenya
  fingolimod
  ocrevus
  dont want in the column
  remove this drug row
  text mining for drug column
  </code></pre>
  
  <p>I want to create a new dataframe with only correct drug words and removing the garbage. I have tried below solutions, but it gives me a blank/empty column of drug.</p>
  
  <pre><code>df_drug = pd.DataFrame(columns = ['drug'])
  df_drug = df_drug[df_drug.drug.str.count(' ')==1]
  or, df_drug = df_drug[df_drug.drug.str.contains('')]
  </code></pre>
  
  <p>Could you please help me to get the correct solution? Like:</p>
  
  <pre><code>df_drug.head()
  drug
  gilenya
  fingolimod
  ocrevus
  </code></pre>