title: How unique is each row based on 3-4 columns?
body: <p>I am going to merge two datasets soon by 3 columns.
  The hope is that there are no/few 3 column group repeats in the original dataset. I would like to produce something that says approximately how unique each row is. Like maybe some kind of frequency plot (might not work as I have a very large dataset), maybe a table that displays the average frequency for each .5million rows or something like that.</p>
  <p>Is there a way to determine how unique each row is compared to the other rows?</p>
  <pre><code>1   2   3
  A   100 B
  A   200 B
  A   200 B
  
  </code></pre>
  <p>Like for the above data frame, I would like to say that each row is unique</p>
  <pre><code>1    2    3
  A    200  B
  A    200  B
  A    100  B
  
  </code></pre>
  <p>For this data set, rows 1 and 2 are not unique. I don't want to drop one, but I am hoping to quantify/weight the amount of non-unique rows.</p>
  <p>The problem is my dataframe is 14,000,000 lines long, so I need to think of a way I can show how unique each row is on a set this big.</p>