R if statement across columns of data table to populate new column - r

Question

data <- data.frame(dates = c("2014-10-28 00:01:59.526","2014-10-27 13:30:01.526"),
times = c("23:59:59","13:29:55"),
hour = c(23,13),
minute = c(59,29),
second = c(59,55))
data[,1] <- as.POSIXct(data[,1])
data[,2] <- as.factor(data[,2])
class(data[,1])
class(data[,2])
class(data[,3])
class(data[,4])
class(data[,5])
data
dates times hour minute second
1 2014-10-28 00:01:59.526 23:59:59 23 59 59
2 2014-10-27 13:30:01.526 13:29:55 13 29 55
I need to populate a new column "NewDate" with a POSIXct data that is the combination of the date and time column BUT there IF the hour column shows 23 then the date for "NEwDate" should be the date from the "date" column MINUS 1 day otherwise it should be the date from the "date" column.
So the final output should be:
date time hour minute second NewDate
1 2014-10-28 00:01:59.526 23:59:59 23 59 59 2014-10-27 23:59:59 #NewDate = date-1 + time
2 2014-10-27 13:30:01.526 13:29:55 13 29 55 2014-10-17 13:29:55 #NewDate = date + time
(NewDate has to be a POSIXct)
What is the best way to do this WITHOUT looping down the data frame and doing something like:
library(lubridate) #lubridate contains hour(), minute(), second()
CorrectTIME <- function(date, hour, minute, second)
{
NewDate<- vector("numeric",length(date))
for(i in 1:length(date))
{
if(hour[i] > hour(date[i]) )
{
NewDate[i] =ISOdatetime(year(date[i]), month(date[i]), day(date[i])-1, hour[i], minute[i], second[i], tz="GMT")
}else
{
NewDate[i] =ISOdatetime(year(date[i]), month(date[i]), day(date[i]), hour[i], minute[i], second[i], tz="GMT")
}
}
}

Answer 1

with(data, paste ( format( as.Date(dates) - (hour == 23) , "%Y-%m-%d"),
paste( hour, minute, second, sep=":")))
#[1] "2014-10-27 23:59:59" "2014-10-27 13:29:55"
Ooops, forgot the as.POSIXct:
as.POSIXct( with(data, paste ( format( as.Date(dates) - (hour==23) ,
"%Y-%m-%d"), paste( hour, minute, second, sep=":"))) )
[1] "2014-10-27 23:59:59 PDT" "2014-10-27 13:29:55 PDT"