title: Identifying unique codes in a dataframe that also exist in another smaller dataframe
body: <p>I'm new to python and am playing around with some data. I was able to extract identifier codes with a particular error into a smaller data frame. I would like to remove these records from the larger dataset. However, some of the identifier codes have multiple entries, not all with the error. I would still like to remove all occurrences of identifiers codes where one of the errors occurs.</p>
  
  <p>I'm thinking a for loop approach would be best, but might take a long time as each identifier would have to search through the second list.</p>
  
  <p>I'm not sure if I'm thinking about this in the best way possible or not - please advise if you have a better idea or approach to removing these records!</p>