I want to create a new variable in my data table in R that will be equal to 1, if the date of the event is after a certain time (2019-01-01) and will be equal to 0 otherwise. I am using the following code:
dt$time <- ifelse[dt$date > '2019-01-01',1,0]
But I am getting a mistake:
object of type 'closure' is not subsettable.
To be honest, I don't understand what is wrong.
You are using wrong syntax, you probably meant :
dt$time <- ifelse(dt$date > '2019-01-01',1,0)
Even if the above work it will not give you correct output always because you are comparing date with string here (check class('2019-01-01')). You should probably use
dt$time <- ifelse(dt$date > as.Date('2019-01-01'), 1, 0)
but you don't really need ifelse here, you can convert the logical values after comparison to integer values.
dt$time <- as.integer(dt$date > as.Date('2019-01-01'))
#OR
#dt$time <- +(dt$date > as.Date('2019-01-01'))