[R] Counting occurrences in a moving window

[mdvaan]

Thank you very much! I really liked the first solution, it worked great for
my larger dataset.

M



Gabor Grothendieck wrote:
> 
> On Fri, Jun 3, 2011 at 8:11 AM, mdvaan <mathijsdevaan at gmail.com>
> wrote:
>> Would it be possible to use the sqldf package and the ave function to
>> simply
>> run ave over a limited set? So something like:
>>
>> DF = data.frame(read.table(textConnection("  A  B
>> 8025  1995
>> 8026  1995
>> 8029  1995
>> 8026  1996
>> 8025  1997
>> 8026  1997
>> 8025  1997
>> 8027  1997
>> 8026  1999
>> 8027  1999
>> 8028  1995
>> 8029  1998
>> 8025  1997
>> 8027  1997
>> 8026  1999
>> 8027  1999
>> 8028  1995
>> 8029  1998"),head=TRUE,stringsAsFactors=FALSE))
>>
>> library(sqldf)
>> years<-c(1995:1999)
>> for (t in 1:length(years))
>>        {
>>        year = as.numeric(years[t])
>>        m<-sqldf('select * from DF where B between $year-1 AND $year-4')
>>        n<-ave(m$A,m$A,FUN = length)
>>        }
>>
>> How do I get the correct values in DF$C? Thanks!!
> 
> In sqldf it would be like this:
> 
> sqldf("select x.*, sum(x.A = y.A and y.B < x.B and y.B >= x.B-3) C
> from DF x, DF y group by x.rowid")
> 
> 
> -- 
> Statistics & Software Consulting
> GKX Group, GKX Associates Inc.
> tel: 1-877-GKX-GROUP
> email: ggrothendieck at gmail.com
> 
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