title: I want to sort dataframe by duplicates in one column
body: <p>I have df from employers like this:</p>
  <pre><code>data = {'Jobs':['Python-Dev', 'Data Scientist', 'Python-Dev', 'Data Scientist', 'Java-Dev', 'Programmer'], 
      'Skill_01':['python', 'pandas', 'python', 'keras', 'java', 'C++'],
      'Skill_02':['beautifulsoup', 'opencv', 'javascript', 'opencv', 'MySQL', 'nan'],
      'Skill_03':['english B2', 'tensorflow', 'flask', 'nan', 'PostgreSQL', 'nan'],
      'Skill_04':['nan', 'numpy', 'django', 'nan', 'nan', 'nan'],
      'Skill_05':['nan', 'nan', 'sql', 'nan', 'nan', 'nan'],}
  data_df = pd.DataFrame(data)
  </code></pre>
  <p><a href="https://i.stack.imgur.com/IhASY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IhASY.png" alt="enter image description here" /></a></p>
  <p>Different skill requirements because employers are different. Then i want to sort dataframe by duplicates in one column with appending skills-columns.</p>
  <p>I need output like this:</p>
  <p><a href="https://i.stack.imgur.com/IhASY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UUb2H.png" alt="enter image description here" /></a></p>