Dear useRs,
a new and much improved version of the zoo package for indexed totally
ordered observations (such as irregular time series) is available from
CRAN. It allows indexing observations with time/index vectors of arbitrary
class and extends many of the standard generic functions also available
for "ts" objects. Additionally, it allows conversion from/to other
(irregular) time series classes such as "its" and "irts". A
vignette that
explains the features of zoo is also available in the package. For further
details see also the list of changes below.
Seasonal greetings,
Z
Changes in Version 0.9-1
o new generic functions ORDER() and MATCH() (with
order() and match() as the default) so that zoo()
can handle arbitrary index/time classes when
suitable methods for the generic function c(),
length(), order(), match() and subsetting [, are
supplied.
o improved printing of "zoo" objects and added
a summary() method.
o extended coercion functionality to and from
"zoo" objects. "its" objects can be coerced to
"zoo" and vice versa. "zoo" objects can be
coerced to vector, matrix, data.frame or list.
o added functionality to extract/assign to
the coredata() of a "zoo" object.
o added/improved functionality to extract/assign
to the window() of a "zoo" object.
o added/improved functionality to extract/assign
to the index() or time() of a "zoo" object.
o added lag(), diff(), start(), end(), head(),
tail() methods.
o improved plot.zoo() by more flexible expansion
of plotting parameters such as col, lty and pch.
o added a cbind() method for "zoo" objects (almost
synonymous with merge())
o NA handling for "zoo" objects via na.omit(),
na.contiguous(), na.approx() and na.locf().
o na.locf() generic function with default method (suitable
for "zoo" objects) which implements Last Observation
Carried Forward.
o na.approx() generic function with default method (suitable
for "zoo" objects) which implements elimination of NAs
by interpolation.
o added mathematical methods: group generic functions
for "zoo" objects, t(), cumsum(), cumprod(), cummin(),
and cummax().
o added model.frame.AsIs and model.frame.zoo to support
regression based on zoo objects, in particular with lm()
(but also many other regression functions).
o Zero length vector zoo objects may have non-zero index vectors
intended to be used in merge to extend zoo objects. zoo
changed to enable the creation of such objects by omitting
first argument.
o added a vignette explaining the new features
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