Hello,
Two alternative approaches - mutate() vs. sapply() - were used to get the
desired results (i.e., creating a new column of the most recent date from 4
dates ) with help from Arun and Mark on this forum. I now find that the two
data objects (created using two different approaches) are not identical
although results are exactly the same.
identical(new1, new2)
[1] FALSE
Please see the reproducible example below.
I don't understand why the code returns FALSE here. Any hints/comments will
be appreciated.
Thanks,
Pradip
############################################# reproducible example
########################################
library(dplyr)
# data object - description
temp <- "id mrjdate cocdate inhdate haldate
1 2004-11-04 2008-07-18 2005-07-07 2007-11-07
2 NA NA NA NA
3 2009-10-24 NA 2011-10-13 NA
4 2007-10-10 NA NA NA
5 2006-09-01 2005-08-10 NA NA
6 2007-09-04 2011-10-05 NA NA
7 2005-10-25 NA NA 2011-11-04"
# read the data object
example.data <- read.table(textConnection(temp),
colClasses=c("character", "Date", "Date", "Date", "Date"),
header=TRUE, as.is=TRUE
)
# create a new column -dplyr solution (Acknowledgement: Arun)
new1 <- example.data %>%
rowwise() %>%
mutate(oldflag=as.Date(max(mrjdate,cocdate, inhdate, haldate,
na.rm=TRUE),
origin='1970-01-01'))
# create a new column - Base R solution (Acknowlegement: Mark Sharp)
new2 <- example.data
new2$oiddate <- as.Date(sapply(seq_along(new2$id), function(row) {
if (all(is.na(unlist(example.data[row, c('mrjdate','cocdate', 'inhdate',
'haldate')])))) {
max_d <- NA
} else {
max_d <- max(unlist(example.data[row, c('mrjdate','cocdate', 'inhdate',
'haldate')]), na.rm = TRUE)
}
max_d}),
origin = "1970-01-01")
identical(new1, new2)
# print records
print (new1); print(new2)
Pradip K. Muhuri
SAMHSA/CBHSQ
1 Choke Cherry Road, Room 2-1071
Rockville, MD 20857
Tel: 240-276-1070
Fax: 240-276-1260
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Muhuri, Pradip (SAMHSA/CBHSQ)
Sent: Sunday, November 09, 2014 6:11 AM
To: 'Mark Sharp'
Cc: [email protected]
Subject: Re: [R] Getting the most recent dates in a new column from dates in
four columns using the dplyr package (mutate verb)
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:[email protected]]
Sent: Sunday, November 09, 2014 3:01 AM
To: Muhuri, Pradip (SAMHSA/CBHSQ)
Cc: [email protected]
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: [email protected]
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