splitting date and time in data frame [duplicate] - r

Question

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Split date-time column into Date and time variables
(7 answers)
Closed 3 years ago.
I have a column list of dates in data frame with date format 201001011200 as %Y%m%d%H%M. I wanted to split them as %Y%m%d and %H%M as Date and Time.
I tried to as.Date(data$Date,origin = "1970-01-01") but I got an error message
Error in charToDate(x) : character string is not in a standard
unambiguous format
The class of the date is numeric. So I tried to convert it to characterand applied the above as.Date function but was not helpful.
Any idea? Thank you in advance.
EDIT
Here is a sample of my data:
Index Date rank amount
81211 201004090000 11 4.9
81212 201004090100 11 4.6
81213 201004090200 11 3.3
81214 201004090300 11 2.7
81215 201004090400 11 3.1
81216 201004090500 11 3.7
81217 201004090600 11 4.0
81218 201004090700 11 4.2
81219 201004090800 11 4.2
81220 201004090900 11 4.0

Answer 1

Updated Answer: Beginning with your example data, you can do
data$Date <- as.POSIXct(as.character(data$Date), format = "%Y%m%d%H%M")
to change the column to a POSIX datetime value. Then, to extract the date and time into two separate columns, you can do
data$date <- as.character(as.Date(data$Date))
data$time <- format(data$Date, "%T")
This gives the following updated data frame data
Index Date rank amount date time
1 81211 2010-04-09 00:00:00 11 4.9 2010-04-09 00:00:00
2 81212 2010-04-09 01:00:00 11 4.6 2010-04-09 01:00:00
3 81213 2010-04-09 02:00:00 11 3.3 2010-04-09 02:00:00
4 81214 2010-04-09 03:00:00 11 2.7 2010-04-09 03:00:00
5 81215 2010-04-09 04:00:00 11 3.1 2010-04-09 04:00:00
6 81216 2010-04-09 05:00:00 11 3.7 2010-04-09 05:00:00
7 81217 2010-04-09 06:00:00 11 4.0 2010-04-09 06:00:00
8 81218 2010-04-09 07:00:00 11 4.2 2010-04-09 07:00:00
9 81219 2010-04-09 08:00:00 11 4.2 2010-04-09 08:00:00
10 81220 2010-04-09 09:00:00 11 4.0 2010-04-09 09:00:00
Original Answer: If you are starting with a numeric value, wrap it in as.character() then run it through as.POSIXct() to get a POSIX date-time value.
data$Date <- as.POSIXct(as.character(data$Date), format = "%Y%m%d%H%M")
As an example I will use 201001011200 as you gave.
(x <- as.POSIXct(as.character(201001011200), format = "%Y%m%d%H%M"))
# [1] "2010-01-01 12:00:00 PST"
Then to separate out the date and time you can do the following.
list(as.Date(x), format(x, "%T"))
# [[1]]
# [1] "2010-01-01"
#
# [[2]]
# [1] "12:00:00"
That gives Date and character classed items, respectively. For a plain old character vector, just use format() twice.
c(format(x, "%m-%d-%Y"), format(x, "%T"))
# [1] "01-01-2010" "12:00:00"
or
c(as.character(as.Date(x)), format(x, "%T"))
# [1] "2010-01-01" "12:00:00"