[R] help with for loop: new column giving count of observation for each SITEID

[Bert Gunter]

Care to tell us why you think you need such an index? I suspect you do not.

Cheers,
Bert



On Tue, Oct 30, 2012 at 12:21 PM, Meredith, Christy S -FS
<csmeredith at fs.fed.us> wrote:
> Not quite,
>  I need it like this, a new number for each ordered year in the sequence within each site, regardless of what the years are,  and to retain the RchID column.
>
> RchID   site    year    index
> 1       A       2002    1
> 2       A       2004    2
> 3       A       2005    3
> 4       B       2003    1
> 5       B       2006    2
> 6       B       2008    3
> 7       C       2002    1
> 8       C       2003    2
> 9       C       2004    3
>
>
> Thanks so much for you help!
>
> -----Original Message-----
> From: William Dunlap [mailto:wdunlap at tibco.com]
> Sent: Tuesday, October 30, 2012 1:07 PM
> To: Meredith, Christy S -FS; r-help at R-project.org
> Subject: RE: [R] help with for loop: new column giving count of observation for each SITEID
>
> Is this what you want?
>   > withinGroupIndex <- function(group, ...) ave(integer(length(group)), group, ..., FUN=seq_along)
>   > site <- c("A","A","C","D","C","A","B")
>   > data.frame(site, index=withinGroupIndex(site))
>     site index
>   1    A     1
>   2    A     2
>   3    C     1
>   4    D     1
>   5    C     2
>   6    A     3
>   7    B     1
>
> You can add more arguments if the groups depend on more than one value:
>   > year <- rep(c(1985, 2012), c(4,3))
>   > data.frame(site, year, index=withinGroupIndex(site, year))
>     site year index
>   1    A 1985     1
>   2    A 1985     2
>   3    C 1985     1
>   4    D 1985     1
>   5    C 2012     1
>   6    A 2012     1
>   7    B 2012     1
>
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
>
>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org
>> [mailto:r-help-bounces at r-project.org] On Behalf Of Meredith, Christy S
>> -FS
>> Sent: Tuesday, October 30, 2012 11:17 AM
>> To: r-help at R-project.org
>> Subject: [R] help with for loop: new column giving count of
>> observation for each SITEID
>>
>>
>> Hello,
>> I think this is easy, but I can't seem to find a good way to do this
>> in the R help. I have a list of sites, with multiple years of data for
>> each site id. I want to create a new column that gives a number
>> describing whether it is the 1st year ("1" ) the data was collected
>> for the site, the second year ("2"), etc. I have different years for
>> each siteid, but I don't care which year it was collected, just the order that it is in for that siteid.  This is what I have so far, but it doesn't do the analysis separately for each SiteID.
>>
>> indexi<-indexg[order(indexg$SiteID,indexg$Yr),]
>>
>> obs=0
>> indexi=na.omit(indexi)
>> for(i in 1:length(indexi$SiteID)){
>> obs=obs+1
>> indexi$obs[i]=obs
>> }
>>
>>
>> Thanks for any help you can give.
>>
>> Christy Meredith
>> USDA Forest Service
>> Rocky Mountain Research Station
>> PIBO Monitoring
>> Data Analyst
>> Voice: 435-755-3573
>> Fax: 435-755-3563
>>
>>
>>
>>
>>
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>> 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.



-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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