[R] Date code conversion

[Mark Knecht]

On Sat, Jul 4, 2009 at 12:24 PM, Mark Knecht<markknecht at gmail.com> wrote:
> On Sat, Jul 4, 2009 at 12:10 PM, Allan Engelhardt<allane at cybaea.com> wrote:
>> Try help("strptime").  Example
>>
>> strptime(1080103L + 19e6L, "%Y%m%d")
>> # [1] "2008-01-03"
>>
>> (This assumes your input is an integer but you can just drop the L if you
>> want)
>>
>>
>> On 04/07/09 19:37, Mark Knecht wrote:
>>
>> Hi,
>>    Is there a function that will convert this sort of date code which
>> looks like "years from 1900 + month_number + day_number" with no
>> spaces? As an example Jan. 3rd 2008 would be written as 1080103.
>>
>> Thanks,
>> Mark
>
> Thanks. I'm building the program now that dumps all the data to csv
> and wanted to make sure that I could handle this in R instead of the
> app that's generating the data as it seems to be very slow at stuff
> like these conversions. Looks to me like it should work so I keep
> moving forward and maybe have some data in R in the next hour or two
> to test.
>
> Cheers,
> Mark
>

Actually, I got there faster than I thought.

The conversion works with one caveat that's been bothering me as I
learn R. On this Win Vista machine R doesn't seem to know about the
time zone and I don't know how to set it up correctly.

> Sys.timezone()
[1] "GMT"
>

I'm not GMT but rather PST or something like that. Win Vista says I'm
GMT-8 for California, the I.O.U. state, but how do I get the platform
to recognize that?

The next problem is that the command appends GMT, which I don't ant,
but neither do I want PST or whatever it would give me. ?strptime
suggests usetz=FALSE but that doesn't seem to be accepted. See the
example below.

Anyway, we're very close and I appreciate your help.

Cheers,
Mark

> TrackTrades$EnDate
 [1] 1080103 1080107 1080107 1080107 1080107 1080107 1080108 1080108
1080108 1080109
> strptime(TrackTrades$EnDate + 19e6L, "%Y%m%d", tz="", usetz=FALSE)
Error in strptime(TrackTrades$EnDate + 19000000L, "%Y%m%d", tz = "",
usetz = FALSE) :
  unused argument(s) (usetz = FALSE)
> TrackTrades$EnDate
 [1] 1080103 1080107 1080107 1080107 1080107 1080107 1080108 1080108
1080108 1080109
> strptime(TrackTrades$EnDate + 19e6L, "%Y%m%d", tz="")
 [1] "2008-01-03 GMT" "2008-01-07 GMT" "2008-01-07 GMT" "2008-01-07
GMT" "2008-01-07 GMT" "2008-01-07 GMT" "2008-01-08 GMT" "2008-01-08
GMT" "2008-01-08 GMT" "2008-01-09 GMT"