extRemes              package:extRemes              R Documentation

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_D_e_s_c_r_i_p_t_i_o_n:

     'extRemes' is a graphical user interface (GUI) for modeling
     extreme values with the purpose of providing a pedagogical tool
     for scientists who are unfamiliar with extreme value theory or
     extreme value software.  It is not designed to teach the R
     programming language; although, R command lines invoked by the GUI
     dialogs are printed to a log file (extRemes.log) in the current
     working directory.  This package relies heavily on the 'ismev'
     package, and most of the underlying functions are from this
     package.  'ismev' is an R port of Stuart Coles' S-Plus extreme
     value statistical routines.

     For help using 'extRemes', please see the tutorial at:

     <URL: http://www.assessment.ucar.edu/toolkit>

     Also, please consider registering at this site.  We need to
     determine if enough people are using the package to continue with
     its maintenance and development.

     Extreme Value Statistics:

     Extreme value statistics are used primarily to quantify the
     stochastic behavior of a process at unusually large (or small)
     values. Particularly, such analyses usually require estimation of
     the probability of events that are more extreme than any
     previously observed. Many fields have begun to use extreme value
     theory and some have been using it for a very long time including
     meteorology, hydrology, finance and ocean wave modeling to name
     just a few.

     Example Datasets:

     There are several example datasets included with this toolkit.  In
     each case, it is possible to load these datasets into R using the
     'data' function.  Use the 'as.extRemesDataObject' function to
     coerce these data to the form that the GUI windows can recognize
     when loading data in this way.  Generally, it is possible to load
     all of these datasets using the GUI windows (File -> Read Data ->
     browse to data and select -> choose R source -> OK).  The example
     datasets will be in the data directory of the 'extRemes' file
     structure.  It is not necessary to unzip any files to do this; if
     you find yourself unzipping files, you have chosen the wrong file!
      The example datasets included with 'extRemes' are:

     Denmint - Denver daily minimum temperature.

     Flood.dat - U.S. Flood damage (in terms of monetary loss) ('dat'
     file used as example of reading in common data using the extRemes
     dialog).

     ftcanmax - Annual maximum precipitation amounts at one rain gauge
     in Fort Collins, Colorado.

     HEAT - Summer maximum (and minimum) temperature at Phoenix Sky
     Harbor airport.

     Ozone4H.dat - Ground-level ozone order statistics from 1997 from
     513 monitoring stations in the eastern United States.

     PORTw - Maximum and minimum temperature data (and some covariates)
     for Port Jervis, New York.

     Rsum - Frequency of Hurricanes.

     SEPTsp - Maximum and minimum temperature data (and some
     covariates) for Sept-Iles, Quebec.

     damage - Hurricane monetary damage.

     Denversp - Denver precipitation.

     Flood - R source version of the above mentioned 'Flood.dat'
     dataset.

     FtCoPrec - Precipitation amounts at one rain gauge in Fort
     Collins, Colorado.

     Peak - Salt River peak stream flow.

     Potomac - Potomac River peak stream flow.

     Tphap - Daily maximum and minimum temperatures at Phoenix Sky
     Harbor Airport.

     For more information on any of these datasets, type

     'help( [name_of_dataset])'

     from the R prompt.

     Primary Functions for extRemes:

     As mentioned above, 'extRemes' is primarily a pedagogical tool
     that provides a GUI interface to the 'ismev' package.  Listed
     below is the function to invoke the main toolkit dialog window,
     followed by a few underlying functions provided with 'extRemes'
     that are not provided with 'ismev'.

     'extremes.gui':

     The main toolkit dialog window should appear upon loading extRemes
     with 'library(extRemes)'.  If this window is closed while the
     package is still loaded, use 'extremes.gui()' from the R command
     prompt to re-open the main dialog window.

     --------- The following is targeted at the more advanced R user. 
     It is hoped that a person unfamiliar with R can use this toolkit
     without learning more than a very few R commands; and the tutorial
     at the above website should be sufficient to get started for such
     a user.

     Extremes Data Object:

     For ease of operation, it is convenient to have a special class of
     objects for the GUI windows to operate on.  This class,
     'extRemesDataObject', might be considered an orphaned object in R
     lingo because it does not have the usual method functions
     associated with it-they generally do not make sense for this
     object.  The object simply stores information so that the GUI
     windows know which elements of the object to use in particular
     situations.  It would not, for example, make sense to do 'plot(
     tmp)' (where 'tmp' is an object of class 'extRemesDataObject'
     because there are numerous possible plots depending on what is
     included in the object; it would be tantamount to plotting the
     entire workspace (in some cases).  The 'extRemesDataObject' is a
     list object with, at the very least, a 'data' component that
     includes either a data frame or matrix.  Often it will also have
     'name' and 'file.path' components (whenever data is loaded via the
     GUI windows) which give the name of the original file, which can
     be different from the name of the 'extRemesDataObject' list
     object, and the path to the original file.

     --------

     The Extremes Toolkit is funded by the National Science Foundation
     (NSF) through the NCAR Weather and Climate Impact Assessment
     Science Initiative with additional support from the NCAR
     Geophysical Statistics Project (GSP).

