Convert a mm-yy string "Jan-01" into date format [duplicate]

Question

The date in my original Excel file represents the monthly data in the format of "Jan-01". Of course, I can manually convert them to something more useful in the Excel first and then input that into R.

How can I convert such adate into a Date class in R?

Answer 1

If you want a date class, use as.Date:

x <- "Jan-01"
as.Date(paste("01-", x, sep = ""), format = "%d-%b-%y")

If you want a POSIXct class, consider using lubridate:

library(lubridate)
x <- "Jan-01"
dmy(paste("01-", x , sep =""))

If you want to just rely on base:

x <- "Jan-01"
as.POSIXct(paste("01-", x, sep = ""), format = "%d-%b-%y")

Answer 2

Edit:

The easiest way is to use the yearmon class in zoo:

 require(zoo)
 as.yearmon(x, "%b-%y")
#[1] "Jan 2001"

Somewhat longer method:

 x="Jan-01"
 xs<-strsplit(x, "-")
 xd <- as.Date( xs[[1]][2], paste( xs[[1]][1], "01",  sep="-"), format="%y-%b-%d")
 xd
#[1] "2001-01-01"

If you want to process a string of dates, then you may need to use sapply if picking the second method to make a vector of years and a vector of months