R change integer to three integers

Question

I have this number

20101213 which is a representation of this data 2010 Dec 13th I want to extract the year, month and day numbers from that nu

Answer 1

If you don't want to deal with string representation you could also just use mod function like this:

# using mod
year  = floor(value/10000)
month = floor((value %% 10000)/100)
day = value %% 100

Which will then extract the relevant parts of the number as expected.

Answer 2

You probably want to get this into a date-time format anyways for future computing, so how about:

(x <- strptime(20101213, "%Y%m%d"))
# [1] "2010-12-13 EST"

This will enable you to do computations that you wouldn't have been able to with just the year, month number, and day number, such as grabbing the day of the week (0=Sunday, 1=Monday, ...) or day of the year:

x$wday
# [1] 1
x$yday
# [1] 346

Further, you could easily extract the year, month number, and day of month number:

c(x$year+1900, x$mon+1, x$mday)
# [1] 2010   12   13

Edit: As pointed out by @thelatemail, an alternative that doesn't involve remembering offsets is:

as.numeric(c(format(x, "%Y"), format(x, "%m"), format(x, "%d")))
# [1] 2010   12   13

Answer 3

year <- as.numeric(substr(as.character(value),start = 1,stop = 4))
month <- as.numeric(substr(as.character(value),start = 5,stop = 6))
day <- as.numeric(substr(as.character(value),start = 7,stop = 8))