R help - Nov 2009 - How to setup the tsp attribute of a dataset

Hello,
I am wondering how I should set up the tsp attribute (available through 
attr(x, "tsp")) of a dataset x? Let's assume that x has 100
points, and
I want to set the frequency to 4.
I tried:
 > attr(x,"tsp")<-c(1,100,4)
Error in attr(x, "tsp") <- c(1, 100, 4) :
  invalid time series parameters specified
Is there any other way to set the frequency of the data?
Thanks.
-Samik

The first two components of the tsp vector are in time units as
mentioned in ?tsp . Thus you would want:
> x <- 1:100
> tsp(x) <- c(1, 25.75, 4)
but normally you don't have to set it explicitly in the first place.
Just use ts:
> x <- 1:100
> x.ts <- ts(x, start = 1, frequency = 4)
> tsp(x.ts)
[1]  1.00 25.75  4.00
> x.ts
   Qtr1 Qtr2 Qtr3 Qtr4
1     1    2    3    4
2     5    6    7    8
3     9   10   11   12
4    13   14   15   16
5    17   18   19   20
6    21   22   23   24
7    25   26   27   28
8    29   30   31   32
9    33   34   35   36
10   37   38   39   40
11   41   42   43   44
12   45   46   47   48
13   49   50   51   52
14   53   54   55   56
15   57   58   59   60
16   61   62   63   64
17   65   66   67   68
18   69   70   71   72
19   73   74   75   76
20   77   78   79   80
21   81   82   83   84
22   85   86   87   88
23   89   90   91   92
24   93   94   95   96
25   97   98   99  100


On Fri, Nov 20, 2009 at 5:53 PM, Samik Raychaudhuri <samikr at gmail.com>
wrote:
> Hello,
> I am wondering how I should set up the tsp attribute (available through
> attr(x, "tsp")) of a dataset x? Let's assume that x has 100
points, and I
> want to set the frequency to 4.
> I tried:
>> attr(x,"tsp")<-c(1,100,4)
> Error in attr(x, "tsp") <- c(1, 100, 4) :
> ?invalid time series parameters specified
> Is there any other way to set the frequency of the data?
> Thanks.
> -Samik
>
> ______________________________________________
> 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.
>

tsp is supposed to be applied to a ts object. If you are not using ts
objects then that is your problem.

On Fri, Nov 20, 2009 at 6:43 PM, Samik Raychaudhuri <samikr at gmail.com>
wrote:
> Looks like there is a difference between when I use frequency(x) vs. when I
> use frequency(x.ts). If I try to get the tsp attribute of x by using
attr(x,
> "tsp"), it still shows up as NULL. When I looked at the code of
frequency()
> function (in stats), it seems to be looking at attr(x, "tsp"),
which is
> NULL, so the function returns 1.
> Let me relate the context a bit. I am trying to use the function
> forecast:nsdiffs to perform a Canova-Hansen test for a given dataset. Even
> though I specify the seasonality, in an internal function, frequency(x) is
> used to find seasonality, and since that value is 1 (as I explained above:
> it looks at attr(x, "tsp")), the calculations do not succeed.
>
> On 11/20/2009 4:25 PM, Gabor Grothendieck wrote:
>>
>> Not for me.
>>
>>
>>>
>>> x <- 1:100
>>> x.ts <- ts(x, start = 1, frequency = 4)
>>> frequency(x.ts)
>>>
>>
>> [1] 4
>>
>>
>>
>>
>