Yes. I looked at that feature of zoo. But it forced me to keep track of
fractional months in the "Date" world. Square one. I ended up implementing a
class under the paradigm of whole and fractional months. It allows me to do
all my time arithmetic in ways that accountants expect. For example,
accountants think of the close of business June 30th as being the halfway
point of the year, but it's certainly not half the year "as the crow flies."
-Dan

On Thu, May 20, 2010 at 4:01 AM, Gabor Grothendieck <ggrothendieck@gmail.com
> wrote:

> Note that in the zoo package that as.Date.yearmon has a frac= argument,
> e.g.
>
> > library(zoo)
> > ym <- as.yearmon("2010-01")
> > as.Date(ym, frac = 0.5)
> [1] "2010-01-16"
>
>
> On Wed, May 19, 2010 at 9:56 PM, Daniel Murphy <chiefmurphy@gmail.com>
> wrote:
> >>Much better to implement directly what this is trying to do: i.e. to
> >>have a "halfmonth" time step. This is just the union of two "monthly"
> >>sequences, one on the 1st of each month and another on the 15th of
> >>each month.
> >
> > For some applications that might be true. But not for others. For a month
> > with 31 days, there are 14 days before the 15th of the month and 16 days
> > after the 15th, so, for example, March 16th (specifically noon) rather
> than
> > March 15th would be the halfway point if you define "halfway" in terms of
> > the distances to the beginning and end of the month. For a month with 30
> > days -- like April -- the halfway point would be the instant between the
> > 15th and the 16th of the month. Do you label that instant April 15 or
> April
> > 16?  (I prefer "15".) Don't get me started on February.
> >
> > - Dan Murphy
> >
> >        [[alternative HTML version deleted]]
> >
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> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
>

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