Dear R People: I have two data frames, a.df and b.df as seen here:
> a.df[1:10,] DATE GENDER PATIENT_ID AGE SYNDROME 1 4/16/2009 F 23686 45 RASH ON BODY 2 4/16/2009 F 13840 35 CANT URINATE 3 4/16/2009 M 12895 30 BLURRED VISION 4 4/16/2009 M 18375 33 UNABLE TO VOID 5 4/16/2009 M 2237 44 SOB WEAKNESS 6 4/16/2009 F 21484 41 TOOTH PAINTOOTH PAIN 7 4/16/2009 M 10783 37 RT ARM PAIN 8 4/16/2009 M 12610 65 L FOOT INJURY 9 4/16/2009 F 3495 29 URINARY DIFFICULTIES 10 4/16/2009 F 351 36 PT STS MVA > b.df[1:10,] DATE_OF_DEATH ID 1 4/19/2009 21676 2 4/19/2009 13717 3 4/19/2009 20498 4 4/19/2009 14281 5 4/19/2009 38848 6 4/20/2009 331 7 4/20/2009 4084 8 4/20/2009 19616 9 4/20/2009 17965 10 4/20/2009 11863 > a.df will always be larger than b.df. I want to create a third data frame that is matched on PATIENT_ID from a.df and ID from b.df. If there is no match from a.df$PATIENT_ID to b.df$ID, then we omit the row from the new data.frame. If there is a match, we include the DATE_OF_DEATH column from b.df. I've tried all kinds of tricks, but nothing works exactly as I wish. Thanks in advance, Sincerely, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: erinm.hodg...@gmail.com ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.