Hi:

Perhaps you were looking for something like this:

table(cut(mydata[[1]], breaks=seq(from = as.Date("2008-06-26"),
                                                        to =
as.Date("2009-06-26"), by = 'month')))

2008-06-26 2008-07-26 2008-08-26 2008-09-26 2008-10-26 2008-11-26 2008-12-26

        30         31         31         30         31         30         31

2009-01-26 2009-02-26 2009-03-26 2009-04-26 2009-05-26
        31         28         31         30         31

Considering that your data range from May 2007 to mid-November 2009, a way
to generate monthly tables (or any set of common breaks you want) for all
components of the list can be done as follows:

f <- function(x) table(cut(x, breaks = seq(from = as.Date('2007-05-01'),
                                            to = as.Date('2009-12-01'), by =
'month')))
lapply(mydata, f)

This is simply intended to get you started in case you wanted to map your
problem across multiple list components.

HTH,
Dennis

On Mon, Jan 17, 2011 at 11:16 PM, Simon Kiss <simonjkiss@yahoo.ca> wrote:

> Dear Colleagues,
> I have a data set that looks as below. I'd like to count the number of
> dates in a series of arbitrary ranges (breaks) i.e. not pre-defined breaks
> such as months, quarters or years. table(format()) produces ideally
> formatted output, but table() does not appear to accept arbitrary ranges.
> I also tried converting the dates to numeric and using histogram to try to
> get the data, but that doesn't work either.  Cut appears to accept an
> arbitrary range, but I could only get it to produce NAs.
>
> Any suggestions? Yours, Simon Kiss
>
> mydata<-list(x=seq(as.Date("2007-05-01"), as.Date("2009-09-10"),"days"),
> y=seq(as.Date("2007-06-16"), as.Date("2009-11-12"),"days"))
> table(format(mydata[[1]], "%Y"))
> t_1<-hist(as.numeric(mydata[[1]], breaks=c("14056", "14421")))$counts
> cut(mydata[[1]], breaks=c(as.Date("2008-06-26"), ("2009=06-26")))
>
>
> *********************************
> Simon J. Kiss, PhD
> Assistant Professor, Wilfrid Laurier University
> 73 George Street
> Brantford, Ontario, Canada
> N3T 2C9
> Cell: +1 519 761 7606
>
> ______________________________________________
> R-help@r-project.org mailing list
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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