This is a major release that adds a range of substantial new features and
fixes a number of major and minor bugs.
Breaking changes
* All functions now accept 3-d arrayed data, enabling the possibility of
using them on gridded climate data. A new data set (`cruts4`) has been added
to test this new function.
* Function `<spei>` now accepts non-monthly data (that is, data with frequency
other than 12).
* A thorough set of test functions have been implemented to help developing
new functions without compromising the old results (Thanks to Doug
Freedman who wrote the seminal set of tests).
New features
* More thorough data and options checks have been implemented, and a single
error / warning message is produced containing all the errors upon failure.
* Different verbosity levels are now implemented in all functions: now they
print information about the options being used. A new argument (`verbosity`)
can be used to override this behavior if not wanted.
* Different versions of the Penman-Monteith ETo calculation have been
implemented in function `<penman>`.
* A new option to include CO2 concentration data is now available in function
`<penman>`.
* A new option for when no wind data are available in function `<penman>`.
* `<plot.spei>` has been completely rewritten based on `ggplot2`, solving
some bugs and enabling more flexibility.
Bug fixes
* Several minor bugs in `<thornthwaite>`, `<hargreaves>`, and `<penman>`
functions have been solved (output difference is less than 0.1%).
* A bug in `<spei>` has been solved that resulted in bad cumulative data when
using a non-rectangular kernel, leading to incorrect SPEI values.
SPEI 1.7.2, June 2019 (only on GitHub).
Breaking changes
* Allowing for data with frequency other than 12 in `<spei>` function.
SPEI 1.7.1, June 2017.
Bug fixes
* Corrected an error in `<spei>` function, which was not working when
distribution was Gamma or PeasonIII and using user provided parameters.
(Thanks to Emanuele Cordano, emanuele.cordanogmail.com -- 'ecor')
* Added probability of monthly precipitation = 0 (pze) when using user
provided parameters. (Thanks to Emanuele Cordano).
SPEI Version 1.7, June 2017.
Bug fixes
* Corrected a bug in the \code{\link{kern}} function which resulted in a
multiplicative kernel instead of an additive one such the one expected in
the \code{\link{spei}} and \code{\link{spi}} functions.
* Plotting methods for \code{spei} objects completely rewritten, now using
\code{ggplot2}. Additionally, a bug causing a bad representation of time
series starting in months other than January has been corrected.
SPEI 1.6, September 2013.
Bug fixes
* Corrected an error in the function \code{\link{thornthwaite}} which resulted
in wrong potential evapotranspiration estimates when a multivariate time
series was used as input.
* Corrected an error in the function \code{\link{spi}} which resulted in wrong
handling of zero precipitation months when using the Gamma or PearsonIII
distribution.
* Minor fixes to the \code{\link{spi}} and \code{\link{plot.spei}} functions
to correctly handle \code{spei} objects when they result from a call to
\code{\link{spi}}.
* Modification to the \code{\link{kern}} function, which now yields kernel
coefficients averaging one.
* Corrected an error in the functions \code{\link{spi}} and \code{\link{spei}}
which resulted in ub-pwm method being used irrespective of the value of the
\code{fit} parameter used, when using the 'Gamma' or 'PearsonIII' distributions.
* Minor changes to the documentation.
SPEI 1.5, May 2013.
Bug fixes
* Optimization of function \code{\link{spei}}, now using embed() for
accumulating the data at the desired time scale.
SPEI 1.4, May 2013.
Bug fixes
* Minor fixes to functions \code{\link{penman}} and \code{\link{pwm}}.
* Documentation of the \code{\link{penman}} function defined by mistake ed as
the saturation vapor pressure, while it should read 'actual vapor pressure'.
* Function \code{\link{zzz.R}} added to display basic information about the
SPEI package at startup.
* Function \code{\link{SPEINews}} added to display the NEWS file.
SPEI 1.3, March 2013.
Bug fixes
* Minor fixes to functions \code{\link{spei}} and \code{\link{penman}}.
* Added new option for user-supplied SPEI parameters in the \code{\link{spei}}
function. This overrides the fitting of a probability function to the data.
* Added new dataset \code{\link{cabinda}} from Allen et al. (1998).
SPEI 1.2, October 2012.
Bug fixes
* Fixed a bug causing several functions to fail when a time series not
belonging to matrix class was provided.
* Function \code{\link{plot.spei}} now distinguishes between calls to
\code{\link{spei}} and \code{\link{spi}} and labels the axis accordingly.
SPEI 1.1, March 2012.
* Functions \code{\link{spei}} and \code{\link{spi}} now yield an object of
class "spei".
* New functions for summarizing and plotting "spei" objects are provided.
* An option to establish a reference period for the computation of the indices
has been implemented in functions \code{\link{spei}} and \code{\link{spi}}.
SPEI 1.0, January 2012.
First release of the SPEI package.