Turning an actual date into an integer value in R

Question

Using R, I want to be able to turn a date in format "2014-12-31" to an integer of 20141231, for the purpose of creating a serial number.

My aim is simply to be able to complete the REVERSE of this user question (Turning an integer string date into an actual date).

Appreciate any help provided.

Solution 1

Simply format the Date in that way, then call as.integer on the result.

R> as.integer(format(Sys.Date(), "%Y%m%d"))
[1] 20151008

---

If your date isn't a Date, and is a character string: either convert it to a Date first, or remove the "-" before calling as.integer.

R> dateString <- "2014-12-31"
R> as.integer(format(as.Date(dateString), "%Y%m%d"))
[1] 20141231
R> as.integer(gsub("-", "", dateString))
[1] 20141231

Solution 2

Or if you already have character dates:

a <- "2015-03-15"
as.integer(gsub(pattern = "-", replacement="", x = a))
#[1] 20150315

Comments

[Qaribbean]

Thank you for a swift reply @joshua-ulrich. In attempting to use this solution I receive the following error: > as.integer(format(testdate, "%Y%m%d")) Error in format.default(testdate, "%Y%m%d") : invalid 'trim' argument

[Roland]

@Qaribbean Your "date" is not a Date variable. Either use as.Date or the suggestion in the other answer.

[Joshua Ulrich]

@Qaribbean: You said you had a date, so I assumed it was a Date object. Apparently, it's just a character string.

[Qaribbean]

@joshua-ulrich My apologies for not clarifying.

[Qaribbean]

@joshua-ulrich Thank you for that updated answer, this is also helpful!