R ifelse avoiding change in date format [duplicate]

Question

This question already has an answer here:

• How to prevent ifelse() from turning Date objects into numeric objects 6 answers

I am trying to make ifesle for two dates. I have two columns- DateIn and DateOut. I need to add 3rd variable, which would show "DateOut" if there is date value, or DateIn if there is :

DateIn     DateOut     Travel date
2010-11-24 <NA>        2010-11-24
2011-12-21 2012-01-21  2012-01-21
2010-10-25 2010-11-25  2010-11-25
2014-01-14 <NA>        2014-01-14

I tried to do that with

TravelDate <- ifelse(is.na(DateIn), DateOut, DateIn)

But the result I am gettin is:

    DateIn     DateOut     Travel date
2010-11-24 <NA>            15018
2011-12-21 2012-01-21      15151
2010-10-25 2010-11-25      14972
2014-01-14 <NA>            14972

Travel date is classified as "logical" Is there a ways how to achieve the rusult withou R transforming date to number?

Thanks a lot!

Answer 1

If dat is the dataset. I assume it is is.na(DateOut) from the Travel date column

 as.Date(with(dat, ifelse(is.na(DateOut), DateIn, DateOut)),origin="1970-01-01")
#[1] "2010-11-24" "2012-01-21" "2010-11-25" "2014-01-14"

Or you can do:

 dat$Travel.date <- dat$DateOut
 dat$Travel.date[is.na(dat$Travel.date)] <- dat$DateIn[is.na(dat$Travel.date)]
  dat
 #      DateIn    DateOut Travel.date
 #1 2010-11-24       <NA>  2010-11-24
 #2 2011-12-21 2012-01-21  2012-01-21
 #3 2010-10-25 2010-11-25  2010-11-25
 #4 2014-01-14       <NA>  2014-01-14

Answer 2

Assign DateOut to Travel.date and then for components of DateOut which are NA replace them with DateIn using replace:

DF2 <- transform(DF, Travel.date = DateOut)
isna <- is.na(DF2$DateOut)
transform(DF2, Travel.date = replace(Travel.date, isna, DateIn[isna]))

We have assumed this test data:

DF <- structure(list(DateIn = structure(c(14937, 15329, 14907, 16084
), class = "Date"), DateOut = structure(c(NA, 15360, 14938, NA
), class = "Date"), Travel.date = structure(c(NA, 15360, 14938, 
NA), class = "Date")), .Names = c("DateIn", "DateOut", "Travel.date"
), row.names = c(NA, -4L), class = "data.frame")

Answer 3

Lets assume this is in a dataframe named 'dat'. I'm guessing your are using 'attach' and I would advise you to drop that misguided approach, since it will trip you up more often than not and the saved time in typing will be wasted by the confusion it creates. Instead it would be quite easy to modify the code the you are using:

dat$TravelDate <- as.Date( with(dat, 
                    ifelse(is.na(DateIn), DateOut, DateIn)), origin="1970-01-01")
dat
      DateIn    DateOut Travel_date TravelDate
1 2010-11-24       <NA>  2010-11-24 2010-11-24
2 2011-12-21 2012-01-21  2012-01-21 2011-12-21
3 2010-10-25 2010-11-25  2010-11-25 2010-10-25
4 2014-01-14       <NA>  2014-01-14 2014-01-14

Data test case. Note that the col name had the space removed:

 dat<- read.table(textConnection("DateIn     DateOut     Travel_date
 2010-11-24 NA        2010-11-24
 2011-12-21 2012-01-21  2012-01-21
 2010-10-25 2010-11-25  2010-11-25
 2014-01-14 NA        2014-01-14"), header=TRUE, colClasses="Date")