[R] [R-pkgs] zoo 0.9-1

Achim Zeileis Achim.Zeileis at wu-wien.ac.at
Thu Dec 23 13:37:25 CET 2004

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,

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

  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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