Find the day of a week

Question

Let's say that I have a date in R and it's formatted as follows. date 2012-02-01 2012-02-01 2012-02-02 Is there any way in R to add another column with the day of the week associated with the date? The dataset is really large, so it would not make sense to go through manually and make the changes. df = data.frame(date=c("2012-02-01", "2012-02-01", "2012-02-02")) So after adding the days, it would end up looking like: date day 2012-02-01 Wednesday 2012-02-01 Wednesday 2012-02-02 Thursday Is this possible? Can anyone point me to a package that will allow me to do this? Just trying to automatically generate the day by the date. Select the correct answer from above options

Answer 1

To extract the weekday, month or quarter, or the Julian time (days since some origin), use the weekdays function that extracts parts of a POSIXt or Date Object. In your case: dt = data.frame(date=c("2012-02-01", "2012-02-01", "2012-02-02")) dt$day <- weekdays(as.Date(dt$date)) dt Output: date day 1 2012-02-01 Wednesday 2 2012-02-01 Wednesday 3 2012-02-02 Thursday