[R] Getting the most recent dates in a new column from dates in four columns using the dplyr package (mutate verb)
David Winsemius
dwinsemius at comcast.net
Thu Dec 4 02:14:21 CET 2014
On Dec 3, 2014, at 2:10 PM, Muhuri, Pradip (SAMHSA/CBHSQ) wrote:
> 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
>
You should have examined the output from dput() on both objects. I think you will find that dplyr is adding new attributes.
Notice the the "mutate()-ed" object now has this class:
class = c("rowwise_df", "tbl_df", "tbl", "data.frame")
Moral: Never rely on the the print representation.
--
David.
> 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: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Muhuri, Pradip (SAMHSA/CBHSQ)
> Sent: Sunday, November 09, 2014 6:11 AM
> To: 'Mark Sharp'
> Cc: r-help at 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)
>
> 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:msharp at TxBiomed.org]
> Sent: Sunday, November 09, 2014 3:01 AM
> To: Muhuri, Pradip (SAMHSA/CBHSQ)
> Cc: r-help at 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: msharp at TxBiomed.org
>
>
>
>
>
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David Winsemius
Alameda, CA, USA
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