Extract weekday from POSIXlt date-time variable

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).

http://stackoverflow.com/questions/9216138/find-the-day-of-a-week-in-r — GSee, Jul 20 '12 at 16:21

score 4 · Accepted Answer · answered Jul 20 '12 at 16:18

4

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)

answered Jul 20 '12 at 16:18

Roland

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Thanks!...and...how would I do hours as well? (into a factor variable) – roody Jul 20 '12 at 16:20

score 0 · Answer 2 · answered Jan 12 '18 at 20:04

0

library(lubridate)
ttt<-strptime("01/12/2018 18:00", "%m/%d/%Y %H:%M")
wday(ttt)
[1] 6 #Sunday=1
wday(ttt,label=TRUE)
[1] Fri

This approach can save you conversion if you need to work with numbers

answered Jan 12 '18 at 20:04

3pitt

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Extract weekday from POSIXlt date-time variable

2 Answers2