title: How to take row values from one pandas dataframe and use them as reference to get values from another dataframe
body: <p>I have two dataframes. One contains contact information for constituents. The other was created to pair up constituents that might be part of the same household.</p>
  <p>Sample:</p>
  <pre><code>data1 = {'Household_0':['1234567','2345678','3456789','4567890'],
          'Individual_0':['1111111','2222222','3333333','4444444'],
          'Individual_1':['5555555','6666666','7777777','']}
  df1=pd.DataFrame(data1)
  
  data2 = {'Constituent Id':['1234567','2345678','3456789','4567890',
                             '1111111','2222222','3333333','4444444',
                             '5555555','6666666','7777777'],
           'Display Name':['Clark Kent and Lois Lane','Bruce Banner and Betty Ross',
                           'Tony Stark and Pepper Pots','Steve Rogers','Clark Kent','Bruce Banner',
                           'Tony Stark','Steve Rogers','Lois Lane','Betty Ross','Pepper Pots']}
  df2=pd.DataFrame(data2)
  </code></pre>
  <p>Resulting in:</p>
  <pre><code>df1
    Household_0 Individual_0 Individual_1
  0     1234567      1111111      5555555
  1     2345678      2222222      6666666
  2     3456789      3333333      7777777
  3     4567890      4444444     
  
  df2
     Constituent Id                 Display Name
  0         1234567     Clark Kent and Lois Lane
  1         2345678  Bruce Banner and Betty Ross
  2         3456789   Tony Stark and Pepper Pots
  3         4567890                 Steve Rogers
  4         1111111                   Clark Kent
  5         2222222                 Bruce Banner
  6         3333333                   Tony Stark
  7         4444444                 Steve Rogers
  8         5555555                    Lois Lane
  9         6666666                   Betty Ross
  10        7777777                  Pepper Pots
  </code></pre>
  <p>I would like to take df1, reference the <code>Constituent Id</code> out of df2, and create a new dataframe that has the names of the constituents instead of their IDs, so that we can ensure they are truly family/household members.</p>
  <p>I believe I can do this by iterating, but that seems like the wrong approach. Is there a straightforward way to do this?</p>