How to get date format in a dataframe column?

Question

I have a dataframe with a date column, and I want to convert it. With this example,

DF <- data.frame(name = paste("A", 1:5, sep = ""), 
                 birth = c("16131", "2014-07-04", "16257", "15982", "2014-07-04"))

as.Date(DF$birth, origin = "1970-01-01")

It's returning me a message error :

Error in charToDate(x) : 
  la chaîne de caractères n'est pas dans un format standard non ambigu

In english, the string is in a ambiguous standard format. Thanks in advance!

You're constructing your data.frame wrong. Values in `birth` are not only dates, but also integers (e.g. 16131). — Roman Luštrik, Jul 08 '14 at 09:16
Do as.Date(16131, origin = "1970-01-01") it will return a date ! — Mostafa90, Jul 08 '14 at 09:20

konvas · Accepted Answer · 2014-07-08T09:33:43.367

The problem is that some of your values require integer to Date conversion and some others character to Date. To complicate it even more, your DF$birth is a factor. You can split it, apply as.Date to the integer parts and the character parts, and then join them:

f <- function(x) {
    # Thanks to @RichardScriven for the improvement
    v1 <- as.numeric(v2 <- as.character(x))
    v1 <- as.Date(v1, origin = "1970-01-01")
    v2[!is.na(v1)] <- NA
    v2 <- as.Date(v2, origin = "1970-01-01")
    as.Date(ifelse(is.na(v1), v2, v1), origin = "1970-01-01")
}

f(DF$birth)
# [1] "2014-03-02" "2014-07-04" "2014-07-06" "2013-10-04" "2014-07-04"

You could avoid repetition by doing `v1 <- as.numeric(v2 <- as.character(DF$birth))`. — Rich Scriven, Jul 08 '14 at 09:31

score 1 · Answer 2 · answered Jul 08 '14 at 09:17

as.Date(DF$birth[1], origin = "1970-01-01")
## Błąd w charToDate(x) : 
##   łańcuch tekstowy nie jest w standardowym jednoznacznym formacie
as.Date(DF$birth[2], origin = "1970-01-01")
## [1] "2014-07-04"

every element of birth column have to match this "1970-01-01" data pattern. Otherwise you will get the error.

score 1 · Answer 3 · answered Jul 08 '14 at 11:13

You may also use:

 library(gsubfn)

 DF$birth <- as.Date(gsubfn("^[[:digit:]]+$",
 ~ format(as.Date(as.numeric(x),origin="1970-01-01"),"%Y-%m-%d"),
   as.character(DF$birth) ))
 DF$birth 
 #[1] "2014-03-02" "2014-07-04" "2014-07-06" "2013-10-04" "2014-07-04"

How to get date format in a dataframe column?

3 Answers3