R help - Jun 2006 - converting to time series object : ts - package:stats

Hi,
   
  I am trying to convert a dataset (dataframe) into time series object using ts
function in stats package. My dataset is as follows:
   
  >df
  [1] 11.08 7.08  7.08  6.08  6.08  6.08  23.08 32.08 8.08  11.08 6.08  13.08
13.83 16.83 19.83 8.83  20.83 17.83
  [19] 9.83  20.83 10.83 12.83 15.83 11.83
   
  I converted this into time series object as follows
   
  >tsdata <-  ts((df),frequency = 12, start = c(1999, 1))
   
  The resulting time series is as follows:

       Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1999   2  15  15  14  14  14  12  13  16   2  14   5
2000   6   8  10  17  11   9  18  11   1   4   7   3

  I am unable to understand why the values of df and tsdata does not match. I
looked at ts function and I couldn't find any data transformation. Am I
missing something here? Any pointers would be of great help.
   
  Thanks in advance.
   
  Sachin

 		
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On Mon, 26 Jun 2006, Sachin J wrote:
>  I am trying to convert a dataset (dataframe) into time series object 
> using ts function in stats package. My dataset is as follows:
>
>  >df
>  [1] 11.08 7.08  7.08  6.08  6.08  6.08  23.08 32.08 8.08  11.08 6.08 
13.08 13.83 16.83 19.83 8.83  20.83 17.83
>  [19] 9.83  20.83 10.83 12.83 15.83 11.83
No data frame will print like that, so it seems that your description and 
printout do not match.
>  I converted this into time series object as follows
>
>  >tsdata <-  ts((df),frequency = 12, start = c(1999, 1))
>From the help page for ts:
     data: a numeric vector or matrix of the observed time-series
           values. A data frame will be coerced to a numeric matrix via
           'data.matrix'.

I suspect you have a single-column data frame with a factor column.
Look up what data.matrix does for factors.
>  The resulting time series is as follows:
>
>       Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
> 1999   2  15  15  14  14  14  12  13  16   2  14   5
> 2000   6   8  10  17  11   9  18  11   1   4   7   3
>
>  I am unable to understand why the values of df and tsdata does not 
> match. I looked at ts function and I couldn't find any data 
> transformation. Am I missing something here? Any pointers would be of 
> great help.
>
>  Thanks in advance.
>
>  Sachin
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  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

On Mon, 26 Jun 2006, Sachin J wrote:
> Hi,
>
>   I am trying to convert a dataset (dataframe) into time series object
> using ts function in stats package. My dataset is as follows:
>
>   >df
>   [1] 11.08 7.08  7.08  6.08  6.08  6.08  23.08 32.08 8.08  11.08 6.08 
13.08 13.83 16.83 19.83 8.83  20.83 17.83
>   [19] 9.83  20.83 10.83 12.83 15.83 11.83
Please provide a reproducible example. You just showed us the print output
for an object, claiming that it is an object of class "data.frame"
which
is rather unlikely given the print output.
>   I converted this into time series object as follows
>
>   >tsdata <-  ts((df),frequency = 12, start = c(1999, 1))
which produces the right result for me if `df' is a vector or a
data.frame:

df <- c(11.08, 7.08, 7.08, 6.08, 6.08, 6.08, 23.08, 32.08, 8.08, 11.08,
        6.08, 13.08, 13.83, 16.83, 19.83, 8.83, 20.83, 17.83, 9.83, 20.83,
        10.83, 12.83, 15.83, 11.83)
ts(df, frequency = 12, start = c(1999, 1))
ts(as.data.frame(df), frequency = 12, start = c(1999, 1))
>   The resulting time series is as follows:
>
>        Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
> 1999   2  15  15  14  14  14  12  13  16   2  14   5
> 2000   6   8  10  17  11   9  18  11   1   4   7   3
>
>   I am unable to understand why the values of df and tsdata does not match.
So are we because you didn't really tell us enough about df...

Best,
Z
> I looked at ts function and I couldn't find any data transformation. Am
> I missing something here? Any pointers would be of great help.
>
>   Thanks in advance.
>
>   Sachin
>
>
> ---------------------------------
>
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>
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