title: How to create data frame with links between data in two different data frames
body: <p>I have one pandas dataframe for persons like:</p>
  
  <pre><code>pid   name   job
    1   Mike     A
    2   Lucy     A
    3   Jeff     B
  </code></pre>
  
  <p>And a second one for jobs like:</p>
  
  <pre><code>id    name
   1       A
   2       B
   3       C
  </code></pre>
  
  <p>What I want to produce is a third dataframe where I list the connections between people and jobs, so in this dummy example the desired result will be:</p>
  
  <pre><code>personid   jobid
         1       1
         2       1
         3       2
  </code></pre>
  
  <p>How can I accomplish this with pandas? I don't understand how to join in this case, since it's not a by row thing...</p>