[R] from list to dataframe

From: <sms13+_at_pitt.edu>
Date: Thu 19 May 2005 - 08:39:26 EST


I was wondering if someone can help me figure out the following: I have two patient datasets, ds1 and ds2. ds1 has fields "patid", "date", and "lab1". ds2 has "patid", "date", and "lab2". I want to find all the patids that have at least 2 dated records for each lab. I started by splitting each dataset by patid, to create ds1.list and ds2.list. Then I did some processing (with sapply) to each list to get the lengths of each patient list item. Then I kind of lost my way and things got messy as I tried to extract just the patids of those with lengths >= 2, convert them to dataframes (which I didn't have much success with), and then merge the two dataframes to get a vector of the desired patids. Any help would be much appreciated.

Thanks,
Steven



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