See aggregate.zoo and maybe ?rollapply
For date manipluations see R News 4/1 help desk article and the table at
the end of that article, in particular.
Suggest you also read and follow the last line on every r-help message
when posting.
On 12/10/06, Alfonso Sammassimo <cincinattikid at bigpond.com>
wrote:> Hi all,
>
> Please forgive this newbie posting to the list for the first time if I
> haven't followed proper procedure. I have read through many of the
archives
> and find them most useful in learning R.
>
> I have ten years daily data (stock closing prices) which I read in zoo
> format. I am having problems coding R to run a count of how many days in
> each month have a price higher than the first day of that month. I then
wish
> to compare counts for all months. Along these lines, is there a simple way
> to index to certain dates(eg first of month, last of month, any specific
> date in one month) and keep looping over each month using such a reference
> point, and then assessing the results for each month?
>
> Any guidance would be sincerely appreciated,
>
> Alfonso Sammassimo
> Melbourne, Australia.
>
> ______________________________________________
> R-help at stat.math.ethz.ch 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.
>