Hi Dr. Ripley, All,

    Thanks for the succinct advice!  Perfectly what I needed!

Jeff,

    Absolutely I agree that this is a dangerous path, and I would never
consider doing it for something that needs to be robust.  But in 'R' type
casting is a bit messed up, so I've come to accept that sometimes something
I called a string might become a factor, a date became a numeric, etc.  Then
I stick in enough catches throughout my functions to deal with it, worst
case.  It is ugly, but I cannot figure out a way to have tight types and
still use 'R'.  Yet, 'R' has so many cool functions (and more added every
day); I'd be silly to throw the baby out with the bathwater.
    So my typical best case or robust solution is to write a parent script
in python (I simply know python best) that handles all data typing, etc.,
then call 'R' once I know that everything is clean.  In this particular case
above where I was asking, this is really for exploratory work.  Once I get a
solution, I will likely handle typing outside of 'R'.

    Thanks for the advice!

                                      Regards,
                                             Mike


---
XKCD <http://www.xkcd.com>



On Wed, Oct 5, 2011 at 11:41 PM, Prof Brian Ripley <ripley@stats.ox.ac.uk>wrote:

> A more portable way (that function only works in some versions of R) is
>
> as.POSIXct(1317857320, origin="1970-01-01")
>
> possibly with a 'tz' argument if you need to restore the timezone.
>
>
> On Wed, 5 Oct 2011, jim holtman wrote:
>
>  Here is what I use:
>>
>> unix2POSIXct(1317857320)
>> [1] "2011-10-05 19:28:40 EDT"
>>
>>
>> unix2POSIXct  <-  function (time) structure(time, class = c("POSIXt",
>> "POSIXct"))
>>
>>
>> On Wed, Oct 5, 2011 at 7:38 PM, Mike Williamson <this.is.mvw@gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>>    In short, I would like to know if there is any way to convert a
>>> numeric
>>> into a date, similar to how strptime() can convert a string to a date
>>> time
>>> class?
>>>
>>>    There are some functions, etc. which don't work well with dates, and
>>> tend to force them into numerics.  I understand that the number it spits
>>> back is the number of seconds since the beginning of 1970 (see the first
>>> few
>>> sentences of the "Details" portion of ?DateTimeClasses).
>>>    However, it's a bit of a hassle to convert that by hand.  I can create
>>> a
>>> function to do this, and it isn't so hard, but I found it hard to believe
>>> such a function didn't already exist, so I wanted to ask the community.
>>>
>>>    As an example, today (Oct 5th 2011 at approximately 4:30pm, Pacific
>>> time) is approximately 1317857320 as a numeric, but I would like to know
>>> how
>>> to go from that number back to the "2011-10-05 16:28:39 PDT" date time
>>> class
>>> which originally generated it.
>>>
>>>                        Thanks!
>>>                              Mike
>>>
>>> ---
>>> XKCD <http://www.xkcd.com>
>>>
>>>        [[alternative HTML version deleted]]
>>>
>>> ______________________________**________________
>>> R-help@r-project.org mailing list
>>> https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help>
>>> PLEASE do read the posting guide http://www.R-project.org/**
>>> posting-guide.html <http://www.R-project.org/posting-guide.html>
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>
>>
>> --
>> Jim Holtman
>> Data Munger Guru
>>
>> What is the problem that you are trying to solve?
>>
>> ______________________________**________________
>> R-help@r-project.org mailing list
>> https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help>
>> PLEASE do read the posting guide http://www.R-project.org/**
>> posting-guide.html <http://www.R-project.org/posting-guide.html>
>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
> --
> Brian D. Ripley,                  ripley@stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~**ripley/<http://www.stats.ox.ac.uk/~ripley/>
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595

	[[alternative HTML version deleted]]

