# [R] Counting occurrences in a moving window

mdvaan mathijsdevaan at gmail.com
Fri Jun 3 21:59:29 CEST 2011

```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
>>
>> 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
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> email: ggrothendieck at gmail.com
>
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