[R] Creating xts objects from csv file

Rui Barradas ru|pb@rr@d@@ @end|ng |rom @@po@pt
Tue Jul 21 20:07:30 CEST 2020


Hello,

I've cc-ed the list.

Yes, I believe that generally speaking, POSIXct is better than POSIXlt. 
POSIXlt is a complicated structure, POSXct is much simpler and gives 
less problems. Datetimes are a problem because they are datetimes but 
POSIXct is a good way of trying to make things simpler. It's also the 
class returned by packages like lubridate, functions ymd_hms and 
similar. SO I think it's the prefered class for problems with datetime 
variables.

Rui Barradas

Às 17:59 de 21/07/2020, Jeff Reichman escreveu:
> Rui
>
> So generally would it be better to us POSIXct than POSIXlt?
>
> Jeff
> -----Original Message-----
> From: Rui Barradas <ruipbarradas using sapo.pt>
> Sent: Tuesday, July 21, 2020 5:58 AM
> To: reichmanj using sbcglobal.net
> Subject: Re: [R] Creating xts objects from csv file
>
> Hello,
>
> Why it didn't work I don't know but the opposite happens to me, I rarely use as.POSIXlt.
> This is because "POSIXlt" objects are complicated, list-like objects. Try
>
> ct <- as.POSIXct("2020-07-21 12:30")
> lt <- as.POSIXlt("2020-07-21 12:30")
>
> attributes(ct)
> unclass(ct)
> attributes(lt)
> unclass(lt)
>
> POSIXlt objects can be usefull when their components are needed but many times the problems are simple and the POSIXct class is simpler.
>
>
> Rui Barradas
>
> Às 00:40 de 21/07/2020, Jeff Reichman escreveu:
>> Rui
>>
>> Yes that worked. I rarely if ever use the POSIXct function . Wonder why POSIXct worded and POSIXlt didn't????
>>
>> JEff
>>
>> -----Original Message-----
>> From: Rui Barradas <ruipbarradas using sapo.pt>
>> Sent: Monday, July 20, 2020 4:37 PM
>> To: reichmanj using sbcglobal.net; r-help using r-project.org
>> Subject: Re: [R] Creating xts objects from csv file
>>
>> Hello,
>>
>> I cannot reproduce the error, your code runs as expected. Try as.POSIXct?
>>
>> Hope this helps,
>>
>> Rui Barradas
>>
>> Às 21:32 de 20/07/2020, Jeff Reichman escreveu:
>>> R-Help Forum
>>>
>>>     
>>>
>>> Starting to work with xts objects but can't figure out what I'm doing
>>> wrong when converting *.csv file with a dtg variable to a *.xts
>>> object. When I'm converting to an appropriate time object all I get
>>> are NA, so that's my first issue.
>>>
>>>     
>>>
>>> dtg <- c("1/5/2010 2:30", "1/5/2010 10:32", "1/5/2010 12:03")
>>>
>>> seq <- c(1,2,3)
>>>
>>>     
>>>
>>> dat <- data.frame(dtg, seq)
>>>
>>>     
>>>
>>> dat$dtg <- as.POSIXlt(dat$dtg, format = "%m/%d/%Y %H:%M")
>>>
>>>     
>>>
>>> dat.xts <- xts(x = dat[,-1], order.by = dat[,1])
>>>
>>>                   
>>>
>>> head(dat.xts)
>>>
>>>     
>>>
>>> Sincerely
>>>
>>>     
>>>
>>> Jeff Reichman
>>>
>>>
>>> 	[[alternative HTML version deleted]]
>>>
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>> --
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