How do I get my dates in standard unambiguous formats if they can't be recognized due to their ambiguous format?

Question

I want to split up a Timestamp from Excel into year and julian day. I know, duplicate question, but combining everything I have found from other questions is not helping me.

The timestamp is formatted 1/13/2011 13:55 . So, I wanted to tell R to recognize this as a time variable. I have hours and minutes so I tried as.POSIXct and as.POSIXlt. These didn't work. I tried adding strptime --

as.POSIXct(strptime(df$TIMESTAMP, "%d/%m/%Y %H:%M%S"))

I just got NAs.

Once I got R to recognize it as a date, I was going to use lubridate like day(df$Date) .

Answer 1

It seems as though you have month and day reversed

 1/13/2011 13:55 

with

"%d/%m/%Y %H:%M%S"

corresponds to the 1st day of the 13th month, which is probably why you're getting NAs. This seems to work for me:

a <- "01/13/2011 13:55"

t <- strptime(a, "%m/%d/%Y %H:%M")
t
"2011-01-13 13:55:00"