title: Split cell into multiple rows in pandas dataframe
body: <p>I have a dataframe contains orders data, each order has multiple packages stored as comma separated string [<code>package</code> &amp; <code>package_code</code>] columns</p>
  
  <p>I want to split the packages data and create a row for each package including its order details</p>
  
  <p>Here is a sample input dataframe:</p>
  
  <pre><code>import pandas as pd
  df = pd.DataFrame({"order_id":[1,3,7],"order_date":["20/5/2018","22/5/2018","23/5/2018"], "package":["p1,p2,p3","p4","p5,p6"],"package_code":["#111,#222,#333","#444","#555,#666"]})
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/ih2hm.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ih2hm.png" alt="Input Dataframe"></a></p>
  
  <p>And this is what I am trying to achieve as output:
  <a href="https://i.stack.imgur.com/GLthN.png" rel="noreferrer"><img src="https://i.stack.imgur.com/GLthN.png" alt="Output"></a></p>
  
  <p>How can I do that with pandas?</p>