Question

Super easy question, that somehow I can’t figure out by reading the documentation.I am reading in a date/time variable into POSIXlt form as follows:

data$date <-strptime(unformatted.date, %m/%d/%Y %H:%M)

Then, I am trying to create a factor variable representing the weekday:

data$weekday <- as.POSIXlt(data$date, format="%A")

This returns a variable that is NA. Help! (And I apologize if this is something most people can get from the documentation…I really have read around, and can’t find the answer).

Answer 1

ttt<-strptime("07/20/2012 18:00", "%m/%d/%Y %H:%M")
ttt
weekdays(ttt)
#[1] "Friday"

This can be found out by reading ?POSIXlt carefully.

PS: factor(ttt$hour)