[R] window?
Dennis Murphy
djmuser at gmail.com
Wed Nov 9 01:20:07 CET 2011
The ets() function in the forecast package requires either a numeric
vector or a Time-Series object (produced from ts()). The frequency
argument in ts() refers to the time duration between observations;
e.g., frequency = 7 means that the data are weekly; frequency = 12
means that the data are monthly; frequency = 4 means that the data are
quarterly. You can see this from the examples on the help page of ts:
?ts at the R prompt.
The example associated with the forecast::ets() function uses the
USAccDeaths data:
data(USAccDeaths)
USAccDeaths ## monthly data for six years
# Simulate the same structure with ts:
u <- ts(rnorm(72), start = c(1973, 1), frequency = 12)
u
# Evidently you want to produce a multivariate series;
# here's one way with monthly frequency:
v <- ts(matrix(rnorm(106), ncol = 2), start = c(2001, 1), frequency = 12)
v
Is that more or less what you were after?
Dennis
On Tue, Nov 8, 2011 at 2:04 PM, Kevin Burton <rkevinburton at charter.net> wrote:
> I expect the frequency to be set to what I set it at and the window to
> return all of the data in the window from the original time series. The
> error is not because it is prime. I can generate a time series with just 52
> values (or 10) and it still occurs. I am building these objects for use with
> the 'forecast' packages and one of the methods 'ets' cannot handle a
> frequency above 24 so I set it (or try to) to 1. Will 'window' take z zoo or
> xts object? Can I convert from zoo or xts to ts?
>
> -----Original Message-----
> From: R. Michael Weylandt [mailto:michael.weylandt at gmail.com]
> Sent: Tuesday, November 08, 2011 2:28 PM
> To: Kevin Burton
> Cc: r-help at r-project.org
> Subject: Re: [R] window?
>
> I'm not entirely sure that your request makes sense: what do you expect the
> frequency to be? It makes sense to me as is...Might your troubles be because
> 53 is prime?
>
> More generally, most people don't like working with the raw ts class and
> prefer the zoo or xts packages because they are much more pleasant for most
> time series work. You might want to take a look into those.
>
> Michael
>
> On Tue, Nov 8, 2011 at 3:18 PM, Kevin Burton <rkevinburton at charter.net>
> wrote:
>> This doesn't seem to work:
>>
>>
>>
>>> d <- rnorm(2*53)
>>
>>> ds <- ts(d, frequency=53, start=c(2000,10))
>>
>>> dswin <- window(ds, start=c(2001,1), end=c(2001,10), frequency=1)
>>
>>> dswin
>>
>> Time Series:
>>
>> Start = 2001
>>
>> End = 2001
>>
>> Frequency = 1
>>
>> [1] 1.779409
>>
>>
>>
>>> dswin <- window(ds, start=c(2001,1), end=c(2001,10))
>>
>>> dswin
>>
>> Time Series:
>>
>> Start = c(2001, 1)
>>
>> End = c(2001, 10)
>>
>> Frequency = 53
>>
>> [1] 1.7794090 0.6916779 -0.6641813 -0.7426889 -0.5584049 -0.2312959
>>
>> [7] -0.0183454 -1.0026301 0.4534920 0.6058198
>>
>>>
>>
>>
>>
>> The problem is that when the frequency is specified only one value
>> shows up in the window. When no frequency is specified I get all 10
>> values but now the time series has a frequency that I don't want.
>>
>>
>>
>> Comments?
>>
>>
>>
>> Kevin
>>
>>
>>
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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