Hi Mark, Your code has also given me the results I expected. Thank you so much for your help.
Regards, Pradip Pradip K. Muhuri, PhD SAMHSA/CBHSQ 1 Choke Cherry Road, Room 2-1071 Rockville, MD 20857 Tel: 240-276-1070 Fax: 240-276-1260 -----Original Message----- From: Mark Sharp [mailto:msh...@txbiomed.org] Sent: Sunday, November 09, 2014 3:01 AM To: Muhuri, Pradip (SAMHSA/CBHSQ) Cc: r-help@r-project.org Subject: Re: [R] Getting the most recent dates in a new column from dates in four columns using the dplyr package (mutate verb) Pradip, mutate() works on the entire column as a vector so that you find the maximum of the entire data set. I am almost certain there is some nice way to handle this, but the sapply() function is a standard approach. max() does not want a dataframe thus the use of unlist(). Using your definition of data1: data3 <- data1 data3$oidflag <- as.Date(sapply(seq_along(data3$id), function(row) { if (all(is.na(unlist(data1[row, -1])))) { max_d <- NA } else { max_d <- max(unlist(data1[row, -1]), na.rm = TRUE) } max_d}), origin = "1970-01-01") data3 id mrjdate cocdate inhdate haldate oidflag 1 1 2004-11-04 2008-07-18 2005-07-07 2007-11-07 2008-07-18 2 2 <NA> <NA> <NA> <NA> <NA> 3 3 2009-10-24 <NA> 2011-10-13 <NA> 2011-10-13 4 4 2007-10-10 <NA> <NA> <NA> 2007-10-10 5 5 2006-09-01 2005-08-10 <NA> <NA> 2006-09-01 6 6 2007-09-04 2011-10-05 <NA> <NA> 2011-10-05 7 7 2005-10-25 <NA> <NA> 2011-11-04 2011-11-04 R. Mark Sharp, Ph.D. Director of Primate Records Database Southwest National Primate Research Center Texas Biomedical Research Institute P.O. Box 760549 San Antonio, TX 78245-0549 Telephone: (210)258-9476 e-mail: msh...@txbiomed.org NOTICE: This E-Mail (including attachments) is confidential and may be legally privileged. It is covered by the Electronic Communications Privacy Act, 18 U.S.C.2510-2521. If you are not the intended recipient, you are hereby notified that any retention, dissemination, distribution or copying of this communication is strictly prohibited. Please reply to the sender that you have received this message in error, then delete it. ______________________________________________ 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.
