R help - Aug 2011 - Time Series data with data every half hour

I am working with data from the USGS with data every 30 minutes from
4/27/2011 to 8/25/2011.

I am having trouble with setting the frequency.

 

My R script is below:

 
> shavers=read.csv("shavers.csv")
> names(shavers)
 [1] "agency_cd"    "site_no"      "datetime"    
"tz_cd"        "Temp"


 [6] "X04_00010_cd" "EC25"         "X05_00095_cd"
"DO"
"X06_00300_cd"

[11] "pH"           "X07_00400_cd"
> as.POSIXct(shavers[1,3])
[1] "2011-04-27 EDT"
> as.POSIXct(shavers[nrow(shavers),3])
[1] "2011-08-25 23:00:00 EDT"
> temp=ts(shavers[,5],as.POSIXct(shavers[1,3]),frequency=48)
Error in attr(data, "tsp") <- c(start, end, frequency) : 

  invalid time series parameters specified

 

I have also used xts:

 
> plot(temp)
> library(xts)
> temp=xts(shavers[,5],order.by=as.POSIXct(shavers[,3]),frequency=48)
> stl(temp,s.window='periodic')
Error in stl(temp, s.window = "periodic") : 

  series is not periodic or has less than two periods

 

The data has very clear daily periods. How can I configure my time
series to analyze this?

 

Thank you very much.


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On 26.08.2011 17:43, Simmons, Ryan wrote:
> I am working with data from the USGS with data every 30 minutes from
> 4/27/2011 to 8/25/2011.
>
> I am having trouble with setting the frequency.
>
>
>
> My R script is below:
>
>
>
>> shavers=read.csv("shavers.csv")
>
>> names(shavers)
>
>   [1] "agency_cd"    "site_no"     
"datetime"     "tz_cd"        "Temp"
>
>
>   [6] "X04_00010_cd" "EC25"        
"X05_00095_cd" "DO"
> "X06_00300_cd"
>
> [11] "pH"           "X07_00400_cd"
>
>> as.POSIXct(shavers[1,3])
>
> [1] "2011-04-27 EDT"
>
>> as.POSIXct(shavers[nrow(shavers),3])
>
> [1] "2011-08-25 23:00:00 EDT"
>
>> temp=ts(shavers[,5],as.POSIXct(shavers[1,3]),frequency=48)
>
> Error in attr(data, "tsp")<- c(start, end, frequency) :
>
>    invalid time series parameters specified
>
>
>
> I have also used xts:
>
>
>
>> plot(temp)
>
>> library(xts)
>
>> temp=xts(shavers[,5],order.by=as.POSIXct(shavers[,3]),frequency=48)
>
>> stl(temp,s.window='periodic')
>
> Error in stl(temp, s.window = "periodic") :
>
>    series is not periodic or has less than two periods
>
>
>
> The data has very clear daily periods.
... but you failed to tell this to the R functions correctly?


> How can I configure my time
> series to analyze this?
We do not know, since we do see a reproducible example you have been 
asked to provide in the posting guide.

Uwe Ligges


>
>
> Thank you very much.
>
>
> 	[[alternative HTML version deleted]]
>
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