Question

R’s base strptime function is giving me output I do not expect.

This works as expected:

strptime(20130203235959, "%Y%m%d%H%M%S")
# yields "2013-02-03 23:59:59"

This too:

strptime(20130202240000, "%Y%m%d%H%M%S")
# yields "2013-02-03"

…but this does not. Why?

strptime(20130203000000, "%Y%m%d%H%M%S")
# yields NA

UPDATE

The value 20130204000000 showed up in a log I generated on a Mac 10.7.5 system using the command:

➜  ~  echo `date +"%Y%m%d%H%M%S"`
20130204000000

UPDATE 2

I even tried lubridate, which seem to be the recommendation:

> parse_date_time(c(20130205000001), c("%Y%m%d%H%M%S"))
 1 parsed with %Y%m%d%H%M%S
[1] "2013-02-05 00:00:01 UTC"
> parse_date_time(c(20130205000000), c("%Y%m%d%H%M%S"))
1 failed to parse.
[1] NA

…and then funnily enough, it printed out “00:00:00” when I added enough seconds to now() to reach midnight:

> now() + new_duration(13000)
[1] "2013-02-10 00:00:00 GMT"

Answer 1

I should use character and not numeric when I parse my dates:

> strptime(20130203000000, "%Y%m%d%H%M%S")    # No!
[1] NA
> strptime("20130203000000", "%Y%m%d%H%M%S")  # Yes!
[1] "2013-02-03"

The reason for this seems to be that my numeric value gets cast to character, and I used one too many digits:

> as.character(201302030000)
[1] "201302030000"
> as.character(2013020300000)
[1] "2013020300000"
> as.character(20130203000000)
[1] "2.0130203e+13"       # This causes the error: it doesn't fit "%Y%m%d%H%M%S"
> as.character(20130203000001)
[1] "20130203000001"      # And this is why anything other than 000000 worked.

---

A quick lesson in figuring out the type you need from the docs: In R, execute help(strptime) and see a popup similar to the image below.

• The red arrow points to the main argument to the function, but does not specify the type (which is why I just tried numeric).
• The green arrow points to the type, which is in the document’s title.