Question

Dear All I am working with a file which has few years data and I am trying to create an aditional coloumn that reads the year and month info from the date coloumn (e.g. 01/01/1997 12:00) and create a new coloumn with month and year together(e.g. Jan-97).

I am not sure how to proceed with this but what I am trying to code is the coloumn with name “new_date” in the following picture:

My sample data:

Data <-
structure(list(date = structure(c(1L, 4L, 7L, 2L, 5L, 8L, 3L, 
6L, 9L), .Label = c("01/01/1997 12:00", "01/01/1998 15:00", "01/01/1999 18:00", 
"01/02/1997 13:00", "01/02/1998 16:00", "01/02/1999 19:00", "01/03/1997 14:00", 
"01/03/1998 17:00", "01/03/1999 19:00"), class = "factor"), value = c(29L, 
31L, 42L, 42L, 52L, 61L, 57L, 55L, 56L)), .Names = c("date", 
"value"), row.names = c(NA, -9L), class = "data.frame")

I would really appreciate if you could advise me about how should I proceed with this.

Answer 1

take a look at ?strptime for the correct formatting.

first make your date column a date:

dat$date <- as.POSIXct(dat$date, format='%d/%m/%Y %H:%M')

then make your new column with the formatting you want:

dat$pretty.date <- format(dat$date, format='%b-%y')

> dat$pretty.date
[1] "Jan-97" "Feb-97" "Mar-97" "Jan-98" "Feb-98" "Mar-98" "Jan-99" "Feb-99" "Mar-99"