[R-sig-finance] More info: zoo 0.9-1

[Achim Zeileis]

Dear finance useRs,

you will probably have seen my post to R-packages that a new and much
improved version of the zoo package for indexed totally ordered
observations (such as irregular time series) is available from CRAN.

As there has been some discussion on this list about the topic of
irregular time series, I would like to add a few comments:
The focus of zoo is 1) to extend standard generic functions and 2) be
independent of a particular class for the time/index information. For
example, it allows the usage of the "Date" class which might be somewhat
more convenient for daily observations than "POSIXct".

But the purpose of zoo is not to replace other classes like "its",
"timeSeries" or "irts": zoo allows for conversion between these classes
and also aims to be a basic building block when constructing more
specialized solutions for irregular time series.

Another new feature of zoo which fills a gap in R is that it allows for
regression based on zoo series. In particular, it is also possible to fit
dynamic linear regression models (where functions like diff() or lag() are
used in the formula specification). Gabor and I have been struggling a bit
with the design of this feature and the current solution is probably not
the best one possible. Therefore, we would be happy about feedback and
suggestions about this feature in particular but also the package in
general.
So if you don't know yet how to spend the long winter nights between Xmas
and New Year's Eve, you might want to enjoy yourselves by trying out the
new zoo package ;-))

In this spirit: seasonal greatings,
Z