################################################################################

Changed in xts 0.13.2:

o Print a message when `period.apply()` is called with `FUN = mean` because it

calculates the mean for each column, not all the data in the subset like it

does for all other functions. The message says to use `FUN = colMeans` for

current behavior and `FUN = function(x) mean(x)` to calculate the mean for

all the data. This information is also included in the help files. The option

`xts.message.period.apply.mean = FALSE` suppresses the message. (#124)

o Fix error when `print.xts()` is called 'quote' or 'right' arguments. (#401)

o Fix `addPolygon()` so it renders when `observation.based = TRUE`. (#403)

o Print trailing zeros for index value with fractional seconds, so every index

value has the same number of characters. (#404)

o Add ability to log scale the y-axis in `plot.xts()`. (#103)

o Actually change the underlying index values when 'tclass' is changed from a

class with a timezone (e.g. POSIXct) to one without a timezone (e.g. Date).

Add a warning when this happens, with a global option to always suppress the

warning. (#311).

o Significantly refactor the internals of `plot.xts()`. (#408)

################################################################################

Changed in xts 0.13.1:

o Ignore attribute order in `all.equal()`. Attribute order shouldn't matter.

That can be checked with `identical()`.

o Only call `tzone()` and `tclass()` once in `check.TZ()`. Calling these

functions multiple times throws multiple warnings for xts objects created

before the tclass and tzone were attached to the index instead of the xts

object. (#306)

o Add instructions to update old objects. Old xts objects do not have tclass

and tzone attributes on the index. Add a function to update the object

attributes and add a note to the warning to show how to use it. (#306)

o Return 'POSIXct' if object has no 'tclass'. An empty string is not a valid

'tclass', so it can cause an error.

o Add notes on `plot.xts()` nomenclature and structure. Also add ASCII art to

illustrate definitions and layout. (#103)

o Remove 'tis' support. The implementation was not even a bare minimum, and

it's not clear it even worked correctly. (#398)

o Register missing S3 methods and update signatures. With R-devel (83995-ish),

`R CMD check` notes these S3 methods are not registered. It also notes that

the signatures for `as.POSIXct.tis()` and `str.replot_xts()` do not match

the respective generics.

It also thinks `time.frequency()` is a S3 method because `time()` is a

generic. The function isn't exported, so renaming won't break any external

code. Thanks to Kurt Hornik for the report. (#398)

o Format each column individually before printing. The top/bottom rows could

have a different number of decimal places and there are often multiple

variying spaces between columns. For example:

close volume ma bsi

2022-01-03 09:31:00 476.470 803961.000 NA 54191.000

2022-01-03 09:32:00 476.700 179476.000 NA 53444.791

2022-01-03 09:33:00 476.540 197919.000 NA -16334.994

...

2023-03-16 14:52:00 394.6000 46728.0000 392.8636 28319.4691

2023-03-16 14:53:00 394.6500 64648.0000 392.8755 15137.6857

2023-03-16 14:54:00 394.6500 69900.0000 392.8873 -1167.9368

There are 4 spaces between the index and the 'close' column, 2 between

'close' and 'volume', 4 between 'volume' and 'ma', and 2 between 'ma' and

'bsi'. There should be a consistent number of spaces between the columns. Most

other classes of objects print with 1 space between the columns.

The top rows have 3 decimals and the bottom rows have 4. These should also be

the same. (#321)

o Only convert printed index values to character. Converting the entire index

to character is time-consuming for xts objects with many observations. It can

take more than a second to print an xts object with 1mm observations.

o Make column names based on number of columns. The original code was a lot

more complicated because it tried to account for truncating the number of

printed columns. That functionality was removed because of how complicated

it was. So now we can simply create printed column names from the number of

columns. (#395)

o Fix `xts()` for zero-row data.frame. The `xts()` constructor would create an

object with a list for coredata when 'x' is a data.frame with no rows. It

needs to convert 'x' to a matrix and throw an error if 'x' is a list. (#394)

o Reduce instances when `dplyr::lag()` warning is shown. The warning was shown

whenever it detected dplyr is installed, even if the user wasn't actively

using dplyr. That caused an excessive amount of noise when other packages

attached xts (e.g. quantmod). Thanks to Duncan Murdoch for the report and

suggested fix! (#393)

o Keep colname when only one non-time-based column. The subset `x[, -which.col]`

would return a vector when the data frame has a time-based column and only

one additional column. Do not drop dimensions, so 'x' will still be a

data.frame in this case. (#391)

o Treat NA the same as NULL for start or end values. NULL represents an

undefined index value. NA represents an unknown or missing index value. xts

does not allow NA as index values. Subsetting an xts or zoo object by NA

returns a zero-length object. So a NA (unknown) index value is essentially

the same as an undefined index value. (#383, #345)

o Warn and remove NA when `periodicity()` called on date-time with NA.

Otherwise the uninformative error below will be thrown. (#289)

Error in try.xts(x, error = "'x' needs to be timeBased or xtsible") :

'x' needs to be timeBased or xtsible

o Account for TZ when making names for `split.xts()`. `as.yearmon.POSIXct()`

always sets `tz = "GMT"` when calling `as.POSIXlt()`, regardless of the xts'

index tzone. That can cause the `as.yearmon()` results to be different days

for GMT and the index's timezone.

Use `format.POSIXct()` for "months" because it checks for a 'tzone' attribute

before converting to POSIXlt and calling `format.POSIXlt()`. The conversion

to POSIXlt is important because it checks and uses the 'tzone' attribute

before considering the 'tz' argument. So it effectively ignores the

`tz = "GMT"` setting in `as.yearmon()`. This is also the reason for calling

`as.POSIXlt()` before calling `as.yearqtr()`. (#392)

################################################################################

Changed in xts 0.13.0:

### New Features

o Added a xts method for `na.fill()` to significantly increase performance when

'fill' is a scalar. (#259)

o `as.xts()` will look for a time-based column in a data.frame if it cannot

create an index from the row names. (#381)

o Change `print()` xts method to only show the first and last 'show.rows' rows

if number of rows is > 'max.rows'. (#321)

o Made `str()` output more descriptive for xts objects. It now differentiates

between xts objects that are empty, zero-width, or zero-length, and defines

each type of object. It also adds column names to the output. (#168, #378)

o Add startup warning that `dplyr::lag()` breaks method dispatch, which means

calls to `lag(my_xts)` won't work any more.

o Added open-ended time of day subsetting ranges. This allows users to subset

by time of day from the start/end of the day without providing the start/end

times (00:00:00.000/23:59:59.999).

For example:

x["/T1800"] # between the start of the day and 5pm

x["T0500/"] # between 5am and the end of the day

Thanks to Chris Katsulis for the suggestion! (#243)

o Updated `to.period()` to accept custom 'endpoints' via the 'period' argument.

Now you can aggregate on something other than the times that 'endpoints()'

supports. Thanks to Ethan B. Smith for the suggestion! (#302)

### Fixes

o Fixed typo and expand `period.apply()` documentation. (#205)

The original description has:

* "the data from INDEX[k] to INDEX[k+1]"

But that's not consistent with the code. It should be:

* "the data from INDEX[k]+1 to INDEX[k+1]"

o Calls to `merge.xts()` on zero-width objects now match `merge.zoo()`.

Previously, `merge.xts()` would return empty xts objects if called on two or

more zero-width xts objects. `merge.zoo()` would return a zero-width object

with the correct index. (#227, #379)

o Fixed `Ops.xts()` so it always returned an object with the same class as the

first (left-hand side) argument. It previously returned an xts object even

if the first argument was a subclass of xts. (#49)

### Other

o Migrated unit tests from RUnit to tinytest. Thanks Mark van der Loo!

o Updated the `endpoints()` documentation to make it clearer that the result

is based on the UNIX epoch (midnight 1970, UTC). Thanks to GitHub user

Eluvias for the suggestion! (#299)

o Fixed `reclass()` to ensure it always adds index attributes from the

'match.to' argument. It was not copying `tclass`, `tzone`, or `tformat` from

'match.to' to the result object. (#43)

o Removed an unnecessary check in `na.locf()` (which is not user-facing).

Thanks to GitHub user @cgiachalis for the suggestion! (#307)

o Updated C entry points so they're not able to accidentally be found via

dynamic lookup (i.e. `.Call("foo", ...)`). This makes each call to the C

code a few microseconds faster, which is nice. (#260)

o Made `merge.xts()` results consistent with `merge.zoo()` for zero-length xts

objects with columns. The result of `merge.xts()` did not include the

columns of any objects that had one or more columns, but zero rows. A join

should include all the columns of the joined objects, regardless of the

number of rows in the object. This is consistent with `merge.zoo()`. Thanks

to Ethan B. Smith for the report and testing! (#222)

################################################################################

Changed in xts 0.12.2:

o `Ops.xts()` no longer changes column names (via `make.names()`) when the two

objects do not have identical indexes. This makes it consistent with

`Ops.zoo()`. (#114)

o Subsetting a zero-length xts object now returns an object with the same

storage type as the input. It previously always returned a 'logical' xts

object. (#376)

o `tclass()` and `tzone()` now return the correct values for zero-length xts

objects, instead of the defaults in the `.xts()` constructor. Thanks to Andre

Mikulec for the report and suggested patch! (#255)

o `first()` and `last()` now return a zero-length xts object when `n = 0`. They

previously returned the entire object. This is consistent with the default

`head()` and `tail()` functions, and data.table's `first()` and `last()`

functions. Thanks to Ethan B. Smith for the report and patch! (#350)

o `plot.xts()` now has a `yaxis.ticks` argument to control the number of y-axis

grid lines, instead of always drawing 5 grid lines. Thanks to Fredrik

Wartenberg for the feature request and patch! (#374)

o Subsetting a zero-width xts now returns an object with the same class, tclass,

tzone, and xtsAttributes as the input. Thanks to @shikokuchuo for the report!

(#359)

o `endpoints()` now always returns last observation. Thanks to GitHub user

Eluvias for the report. (#300)

o Ensure `endpoints()` errors for every 'on' value when `k < 1`. It was not

throwing an error for `k < 1` for `on` of "years", "quarters", or "months".

Thanks to Eluvias for the report. (#301)

o Fix `window()` for yearmon and yearqtr indexes. In xts < 0.11-0, `window.zoo()`

was dispatched when `window()` was called on a xts object because there was no

`window.xts()` method. `window.zoo()` supports additional types of values for the

`start` argument, and possibly other features. So this fixes a breaking change

in xts >= 0.11-0. Thanks to @annaymj for the report. (#312)

o Clarify whether `axTicksByTime()` returns index timestamps or locations (e.g.

1, 2, 3). Thanks to @ggrothendieck for the suggestion and feedback. (#354)

o Fix merge on complex types when 'fill' is needed. `merge()` would throw an

error because it treated 'fill' as double instead of complex. Thanks to

@ggrothendieck for the report. (#346)

o Add a message to tell the user how to disable 'xts_check_TZ' warning. Thanks

to Jerzy Pawlowski for the nudge. (#113)

o Update `rbind()` to handle xts objects without dim attribute. `rbind()` threw

an obscure error if one of the xts objects does not have a dim attribute. We

can handle this case even though all xts objects should always have a dim

attribute. (#361)

o `split.xts()` now always return a named list, which makes it consistent with

`split.zoo()`. Thanks to Gabor Grothendieck for the report. (#357)

o xts objects with a zero-length POSIXct index now return a zero-length POSIXct

vector instead of a zero-length integer vector. Thanks to Jasper Schelfhout

for the report and PR! (#363, #364)

o Add suffixes to output of `merge.xts()`. The suffixes are consistent with

`merge.default()` and not `merge.zoo()`, because `merge.zoo()` automatically

uses "." as a separator between column names, but the default method doesn't.

Thanks to Pierre Lamarche for the nudge. Better late than never? (#38, #371)

Changes to plotting functionality

--------------------------------------------------------------------------------

o You can now omit the data time range from the upper-right portion of a plot

by setting `main.timespan = FALSE`. (#247)

o Fix `addEventLines()` when plotted objects have a 'yearmon' index. The ISO-8601

range string was not created correctly. Thanks to @paessens for the report.

(#353)

o Make 'ylim' robust against numerical precision issues by replacing `==` with

`all.equal()`. Thanks to @bollard for the report, PR, and a ton of help

debugging intermediate solutions! (#368)

o Series added to a panel now extend the panel's y-axis. Previously the y-axis

limits were based on the first series' values and not updated when new series

were added. So values of the new series did not appear on the plot if they

were outside of the original series' min/max. Thanks to Vitalie Spinu for the

report and help debugging and testing! (#360)

o All series added to any panel of a plot now update the x-axis of all panels.

So the entire plot's x-axis will include every series' time index values

within the original plot's time range. This behavior is consistent with

`chart_Series()`. Thanks to Vitalie Spinu for the report and help debugging

and testing! (#360, #216)

o All y-values are now plotted for series that have duplicate index values, but

different data values. Thanks to Vitalie Spinu for the report and help

debugging and testing! (#360)

o Adding a series can now extend the x-axis before/after the plot's existing

time index range, so all of the new series' time index values are included in

the plot. This is FALSE by default to maintain backward compatibility. Thanks

to Vitalie Spinu for the report and help debugging and testing! (#360)

################################################################################

Changed in xts 0.12.1:

o Various function could change the tclass of xts objects. This would happen

in calls to reclass(), period.apply(), and for logical operations on

POSIXct indexes. Thanks to Tom Andrews for the report and testing, and to

Panagiotis Cheilaris for contributing test cases (#322, #323).

o plot.xts() now supports y-axis labels via 'ylab'. Thanks to Jasen Mackie

for the suggestion and PR (#333, #334).

o The API header has been updated to fix the signatures of do_merge_xts() and

is_xts, which did not return a SEXP as required of functions callable by

.Call(). Thanks to Tomas Kalibera for the report (#317), and Dirk

Eddelbuettel for the PR (#337). This is a breaking change, but is required

to avoid the potential for a segfault.

o Michael Chirico added an internal isUTC() function to recognize many UTC-

equivalent time zones (#319).

o first() now operates correctly on non-xts objects when 'n = -1'. Previously

it would always return the last two values. Thanks to GitHub user vxg20

for the report (#325).

o The .xts() constructor would create an xts object with row names if 'x' had

row names. This shouldn't happen, because xts objects do not have or

support row names (#298).

o Claymore Marshall added many examples of time-of-day subsetting to

?subset.xts. He also fixed a bug in time-of-day subsetting where subsetting

by hour only returned wrong results (#304, #326, #328).

Changed in xts 0.12-0:

o All the index-attributes have been removed from the xts object and are now

only attached to the index itself (#245). We took great care to maintain

backward compatibility, and throw warnings when deprecated functions are

called and when index-attributes are found on the xts object. But there

still may be some breaking changes lurking in edge cases.

o @SamoPP found one edge case (#297) where an error was thrown when index()

was called on an xts object with an index that had no tclass attribute.

o ...which led Joshua to find that the index setting functions did not

always copy index attributes (#305).

o Several binary operations (e.g. +, -, !=, <, etc.) on variations of

uncommon xts objects with other xts, matrix, or vector objects, could

result in malformed xts objects (#295). Some examples of the types of

uncommon xts objects: no dim attribute, zero-width, zero-length.

o Calling as.matrix() on an xts object without a dim attribute no longer

throws an error (#294).

o merge.xts() now honors check.names = FALSE (#293).

o The possible values for major.ticks, minor.ticks, and grid.ticks.on in the

Details section of ?plot.xts have been corrected. Thanks to Harvey Smith

(@harvey131) for the report and patch (#291).

o as.zoo.xts() is now only registered for zoo versions prior to 1.8-5. Methods

to convert an object to another class should reside in the package that

implements the target class. Thanks to Kurt Hornik for the report (#287).

o .parseISO8601() no longer has a potential length-1 logical error. Thanks to

Kurt Hornik for the report (#280).

o endpoints() now honors k > 0 when on = "quarters". Thanks to @alkment for

the report (#279).

o Performance for the period.XYZ() functions (sum, prod, min, max) is much

faster (#278). Thanks to Chris Katsulis for the report, and Harvey Smith

(@harvey131) for several examples.

o merge.xts() now creates shorter column names when passed unnamed objects.

This is now consistent with zoo (#248).

o Time-of-day performance is ~200x faster, thanks to StackOverflow

user3226167 (#193).

Changed in xts 0.11-2:

o The to.period() family of functions now use the index timezone when

converting intraday index values to daily values (or lower frequency).

Thanks to Garrett See and Gabor Grothendieck for the reports (#53, #277).

o Make column names for merge() results with unnamed objects shorter and more

like zoo (#248). This also makes na.fill() much faster (#259).

BREAKING: This may break existing code for integer unnamed objects.

o Fix subset when 'index(x)' and 'i' contain duplicates. Thanks to Stack

Overflow user 'scs' (https://stackoverflow.com/users/4024268/scs) for the

report, and Philippe Verspeelt for debugging (#275).

o Fix if-statement in xts constructor that may use a logical with length > 1.

Thanks to @HughParsonage for the report and PR (#270, #272).

o Register shift.time.xts() method. Thanks to Philippe Verspeelt for the

report and PR (#268, #273).

o Conditionally register S3 methods for as.timeSeries.xts() and as.fts.xts()

when their respective packages are available (as requested by CRAN). Note

that this means these two functions are no longer exported. This may break

some existing code that calls the methods directly, though 'best practice'

is to let method dispatch determine which method to invoke.

Changed in xts 0.11-1:

o Fix regression in .xts() that caused 'tclass' argument/attribute to be

incorrectly set to POSIXct regardless of user-provided value. Thanks to

@Eluvias for the report and Tom Andrews for the PR (#249, #250).

o Fix performance regression when xts object is subset by a date-time vector.

Thanks to Tom Andrews for the report, and the PR to fix the bug in my patch

(#251, #263, #264).

o Restore behavior from 0.10-2 so subsetting an empty xts object by a date-

time vector returns an empty xts object instead of throwing an error.

Thanks to @alkment for the report (#252).

o Add ability for merge.xts() to handle multiple character or complex xts

objects. Thanks to Ken Williams for the report (#44).

o Add ability to use "quarters" to specify tick/grid mark locations on plots.

This ran but produced an incorrect result in 0.10-2 and threw an error in

0.11-0. Thanks to Marc Weibel for the report (#256).

o Fix illegal read reported by valgrind. Thanks to Tom Andrews for the report

and PR (#236, #264).

Changed in xts 0.11-0:

o Fix make.index.unique() to always return a unique and sorted index. Thanks

to Chris Katsulis for the report and example (#241).

o Add window.xts() method and completely refactor the internal binary search

function it depends on. Thanks to Corwin Joy for the PR, tests, review, and

patience (#100, #240).

o Better axis tick mark locations for plots. Thanks to Dirk Eddelbuettel for

the report (#246). Also incorporate axTicksByTime2() into axTicksByTime() to

reduce code duplication from the migration of quantmod::chart_Series() to

xts::plot.xts() (#74).

o Add details to plot.xts() parameters that are periodicity, now that RStudio

has argument completion. Thanks to Evelyn Mitchell for the PR (#154).

o periodicity() now warns instead of errors if the xts object contains less

than 2 observations (#230).

o first() and last() now keep dims when they would otherwise be dropped by a

regular row subset. This is consistent with head() and tail(). Thanks to

Davis Vaughan for the report (#226).

o Fix subset when ISO8601 string is outside the valid range, so it returns no

data instead of all rows (#96).

o Avoid partial name matches from parse.side() (inside .parseISO8601())

results that are passed to firstof() and lastof(). Thanks to @gp2x for the

report and the patch (#231).

o na.locf.xts() now loops over columns of multivariate objects in C code,

instead of in R. This should improve speed and memory performance. Thanks to

Chris Katsulis and Tom Andrews for their reports and patches (#232, #233,

#234, #235, #237).

o Change plot.xts() default 'pch = 0' (rectangles) to 'pch = 1' (circles) so

it looks more like base and zoo plots (#203).

Changed in xts 0.10-2:

o na.locf.xts() and na.omit.xts() now support character xts objects. Thanks to

Ken Williams and Samo Pahor for the reports (#42).

o na.locf.xts() now honors 'x' and 'xout' arguments by dispatching to the next

method (#215). Thanks to Morten Grum for the report.

o coredata.xts() now functions the same as coredata.zoo() on zero-length

objects, and only removes xts-related attributes (#223). Thanks to Vincent

Guyader for the report.

o plot.xts() no longer ignores 'col.up' and 'col.dn' when 'type="h"' (#224).

Thanks to Charlie Friedemann for the report. This was inadvertently broken

as part of the fix for #210.

Changed in xts 0.10-1:

o 'ylim' values passed to 'addSeries' and 'addPolygon' via '...' are now

captured and honored (#220).

o 'addPolygon' now checks for ylim of zeros, as 'addSeries' does (#164).

o The 'base::as.Date.numeric' method is no longer over-ridden. The exported,

but not registered, method in zoo should prevent any change in behavior.

o Series added to an existing plot are now given the same index values as

the main panel (#216). There still may be some weird behavior if the new

data does not have observations within the timespan of the main panel data,

but no observations on the same timestamps.

o Existing 'par' values are now captured and reset before returning from

plotting functions (#217).

o User-defined 'col' values are now honored when 'type="h"' (#210).

o Values passed to plotting functions are now copied from the calling

environment. This enables plotting arguments to be objects passed

through multiple layers of function calls.

o indexFormat is now generic, consistent with indexFormat<- (#188).

o Calling as.matrix() on a zero-width xts object now behaves consistently

with zoo, and no longer throws an error (#130).

o Fix weird result in merge.xts() when 'fill' argument is NULL or a zero-

length vector (#261).

o Fixed bug in endpoints() due to sub-second representation error via using

integer division (%/%) with non- integer arguments (#202).

o endpoints() gained sub-second accuracy on Windows (#202).

o plot.xts() no longer errors when called on an object containing a constant

value. It chooses ylim values +/-20% from the series value (#156).

o plot.xts() now places y-axis labels in the same location on the plot,

regardless of data periodicity (#85).

o rbind.xts() now throws an error if passed an xts object with different

number of observations in the index and data (e.g., zero-width) (#98).

Changed in xts 0.10-0:

Major changes include:

o A new plot.xts() that is incompatible with earlier versions of plot.xts().

o Moved development from R-Forge to GitHub.

o New xts FAQ.

Other, less disruptive changes include:

o merge.xts() now throws an error if the index contains non-finite values

(#174).

o Constructors xts() and .xts() now ensure order.by and index arguments do not

contain non-finite values. Many xts functions, most notably merge.xts(),

expect all index values to be finite. Missing index values usually indicate

an error, and always occurred at the end of the index (#173, #194, #199).

o Fixed bug in endpoints() when called on sparse data that have the same month

and day, but different years (#169).

o Fixed bug in [.xts did not do the same checks on logical xts objects as it

does for all other data types (#163).

o Fixed bug that caused split.xts() to error if 'f' is a character vector with

more than 1 element (#134).

o Fixed bug that crashed R if 'k' argument to lag.xts() was not an integer and

would be NA when coerced to integer (#152).

o period.apply() now checks to ensure the object's index is unique and sorted,

and sets INDEX <- sort(unique(INDEX)) if it is not. It also ensures INDEX

starts with 0 and ends with NROW(x) (#171).

o All references to the 'its' package have been removed, since it is now

archived on CRAN at the request of its maintainer.

o Fixed bug that crashed R when merge.xts() was called on an empty xts object

and more than one non-xts object (#157).

o Fixed bug that did not set the index's tzone attribute to UTC when

index<-.xts or indexClass<- were called and 'value' did not have a tzone

attribute (#148).

o Fixed a bug in endpoints() that caused incorrect results if the index was

less than the epoch (#144).

o Fixed a bug that caused diff.xts() on a logical xts object to return an

object with a POSIXct index.

o index.xts() works even if the package containing the class for the index

is not attached (it needs to be loaded, however).

o [.xts now returns NA if a one-column xts object is subsect by NA, instead

of throwing an uninformative error (#97).

o Fixed bugs that would crash R when [.xts was called a certain way and 'j'

contained NA values (#97, #181).

o Fixed a bug in endpoints() where 1 second would be subtracted for any date

in the year 1969. The subtraction is only supposed to occur on

1969-12-31 23:59:59.9... to work around behavior in strptime().

o timeBasedSeq() now honors hour/min/sec 'BY' values (#91).

o [.xts now throws an error if 'j' is character and not one of the column

names. This is consistent with [.zoo and [.matrix (#48).

o timeBasedSeq() now works correctly when resolution is "days" the sequence

includes a daylight saving time change (#67).

o Explicitly set indexTZ="UTC" for all index classes that do not have a TZ

(#66). indexTZ="GMT" is also allowed.

o Fixed as.xts() when called on an 'mts' object (#64).

o Moved development from R-Forge to GitHub.

o Fixed bug in to.period() that errored when name=NULL (#5937).

o Fixed bug in .index* functions that did not account for timezones (#5891).

o Fixed bug that allowed index<-.xts to produce an unsorted index (#5893).

o Fixed bug so subsetting a zero-width xts object with a zero-length 'i'

vector no longer returns an object with column names (#5885).

o Updated [.xts to handle 'i' containing multiple zeros (e.g. subsetting by a

"logical" column of an integer xts object).

o endpoints() now errors if k < 0.

Changed in xts 0.9-7:

o Fixed bug that caused logical operators on xts objects to drop the 'tzone'

attribute (#2750).

o Fixed bug that ignored 'which.i' argument to [.xts on zero-width xts

objects (#2753).

o Fixed bug where xts() does not sort 'order.by' if x is missing (#4775).

Changed in xts 0.9-6:

o Fixed bug where setting dimnames to NULL would break as.xts() (#4794).

o Added checks to period.sum/prod/min/max to ensure INDEX is in [0,nrow(x)].

o Fixed missing argument to na_locf() in the C/C++ xtsAPI (Dirk Eddelbuettel).

Changed in xts 0.9-5:

o Increased zoo dependency version to 1.7-10 for changes in C code.

o Fixed several minor issues in the C/C++ xtsAPI (Dirk Eddelbuettel).

Changed in xts 0.9-4:

o Fixed bug where the index was missing the 'tzone' attribute.

o Fixed to.period() bug when 'indexAt' is "firstof" or "lastof". (bug #2691,

patch #2710, thanks to Garrett See)

o Fixed subsetting bug on zero-width xts objects that returned NA data and an

NA index (#2669).

o xts' merge() method now has 'drop' and 'check.names' arguments to match

the zoo merge() method.

o 'index<-' now correctly handles UTC Date objects when resetting index

values. '.index<-' behaved correctly.

o xts' rollapply() method now handles the 'fill' argument.

o Added several functions to the C/C++ API:

- make_index_unique

- make_unique

- endpoints

- do_merge_xts

- na_omit_xts

- na_locf

o Fixed xts' rollapply() method when input has one column, but function

output has more than one column.

Changed in xts 0.9-3:

o No user-visible changes.

Changed in xts 0.9-2:

o Added C/C++ xtsAPI (Dirk Eddelbuettel)

o Added tzone() and tclass() functions as aliases to indexTZ() and

indexClass(), respectively. Eventually will Deprecate/Defunct the former.

Changed in xts 0.9-1:

o xts() now ignores timezone arguments when order.by is Date class, with a

warning.

Changed in xts 0.8-8:

o Modified str() output to make use of proper ISO-8601 range formating

o Fixed bug in reclass() when 'tzone' of object is different than system TZ.

o Fixed bug in xts() that dropped dims when 'x' is a 1-column matrix or

data.frame.

o [.xts no longer warns if 'i' is zero-length.

o to.period() now checks that 'x' is not zero-length/width.

o Fixed edge case in Ops.xts where two objects with no common index create

an invalid 'xts' object with no index.

o to.monthly() and to.quarterly() now default to drop.time=TRUE.

o Internal .drop.time() now changes the index class to Date. This affects

the to.period() family of functions.

o Restore Date index/tclass conversion to POSIXct with a UTC timezone via

integer division instead of double-precision division.

Changed in xts 0.8-6:

o Revert Date index/tclass conversion to POSIXct with a UTC timezone to

previous behavior as in 0.8-2.

Changed in xts 0.8-5:

o A Date index/tclass is now internally converted to POSIXct with a UTC

timezone ensure proper conversion regardless of user TZ settings.

o tclass is now an argument to .xts()

o Fix endpoints() properly handles millisecond time stamps (and microsecond

on not Windows).

o Subsetting zero-width xts objects now behaves like zoo, with NA values

returned for valid row requests.

Changed in xts 0.8-2:

o Fixed bug in lag() and diff() for character coredata.

o Fixed subsetting bug that returned a contiguous chunk of data even when

a non-contiguous 'i' was provided.

o Fixed bug that ignored FinCenter/TZ for timeDate index

o period.apply() now only sets colnames if the number of columns in the input

and output are equal.

o Fixed periodicity() when scale = "yearly"

o Fixed [.xts when row-subsetting via a POSIXct vector, which returned an

object full of NA.

o Added '...' to axis() call inside of plot.xts() to allow for 'cex.axis'

and 'cex.lab' to be passed in.

o Fixed axes=FALSE issue in plot.xts().

o Dependency now on 1.7-0 or better of zoo (R-forge at present)

This build now links to C code moved from xts to zoo. At present

this is only for zoo_lag (used in lag and lagts)

o Added 'drop' and 'fromLast' arguments to make.index.unique().

o Added adj.time() and shift.time()

o Fixed na.locf() bug that would fill trailing NA larger than 'maxgap'

observations (#1319)

o Updated indexFormat() documentation and add an example

Changed in xts 0.8-0:

o Fix print formatting (#1080)

o Fix bug related to na.locf() and zero-width objects (#1079)

o Add .RECLASS = FALSE after '...' for as.xts.*() methods. This makes all

as.xts.*() methods one-way (i.e. not reclass-able). Objects converted to

xts via try.xts() can still be converted back to their original class

via relcass().

o Fix bug that caused colnames to be dropped if object is subset by time

that is not in the index.

Changes in xts 0.7-5:

o try.xts and reclass now are more efficient on xts objects,

no longer appending a .RECLASS attribute. This penalty

(copying) is shifted to classes that are internally converted

to xts.

Changes in xts 0.7-4:

o internal attributes of index are now maintaining

timezone (tzone), time class (tclass) information.

o `[.xts` method is now using new C code. This may revert

back as character-based objects are not supported. Changed

for future code refactoring into zoo, as well as performance

gains on integer, double and logical values. Also added in

checks for NAs. drop=TRUE now works correctly in all known

applications.

o (cbind)merge.xts and rbind.xts now copy index attributes

to handle internal changes to index characteristics (in C code)

o indexTZ.Rd updated to provide information regarding internal

changes. Also indexTZ<- is now exported to facilitate

timezone changing of xts objects.

Changes in xts 0.7-1:

o subsecond ISO8601 subsetting on dates

before 1970 (epoch) is disabled. This is due to a bug

in the R implementation of POSIX handling of fractional

seconds pre-1970. 10 microsecond granularity is still

functional for all other times. Thanks to Andreas Noack Jensen

for the early bug report.

o new 'tzone' arg in xts constructor and 'tz' in .parseISO8601

allows for future support of non-system TZ dependent indexing

o internal index attribute (numeric) now can have attributes

set (tzone is currently the only one used in xts). These should

remain during all xts operations. Still experimental.

o naCheck has been exposed at the C level for use in packages

"LinkingTo: xts". See ?xtsAPI for more details.

Changes in xts 0.7-0:

o A new NEWS file.

o print.xts now passes ...

o endpoints speedup and bug fix (thanks Ismail Onur Filiz)

o na.omit bug on logical and NaN fixes (thanks Fabrizio Pollastri

and Koert Kuipers)

o fromLast=FALSE for na.locf.xts. Matching to zoo. (thanks

to Sandor Benczik)

o LGLSXP support in leadingNA (R fun naCheck)

o fixed logical and NA 'j' subsetting. Thanks Koert Kuipers.

o as.xts and as.timeSeries fixes for timeSeries changes

o merge and subset now support dimensionless xts (non-standard).

merge segfault fixed when merging all 3 or more zero-width xts objects

and only zero-width objects. Thanks to Koert Kuipers for the report.

o added which.i to [.xts to return i values found via

ISO8601 subset string

o new lines.xts and plot.xts, similar to methods in zoo

o lastof now has sec to 10 microsecond precision, and subsec

arg to append to secs.

o xts() further consistency in NROW/index check

o align.time error checks for positive n= values (thanks Brian Peterson)

o toPeriod updates in C, almost exported. ~600-1200x faster

o new lag_xts in C. Increased speed and index flexibility.

o endpoints 'days' bug fix

o .makeISO8601 function to create ISO8601 compliant string

from xts objects