R Package SeaLev

Yves Deville 2023-05-22

Scope

The SeaLev package is a R package funded by IRSN/Behrig. It is devoted to the distribution of a Sea Level random variable (r.v.) say $Z$, viewed as the sum of two independent r.vs $X$ and $Y$ representing the astronomical tide and the surge. More precisely the r.vs relate to a tide interval defined as the time interval separating two consecutive astronomical low tides. Then $X$ is the astronomical high-tide level and $Y$ is the so-called skew surge representing the difference between the observed highest level and the astronomical high tide level.

• The distribution of $X$ can be regarded a perfectly known. More precisely, the support of $X$ is an interval $[x_{\texttt{min}}, , x_{\texttt{max}}]$ where both end-points are finite and known, and $X$ admits a continuous known density $f_X(x)$ on this interval.

• By fitting a Peaks Over Threshold (POT) model from observed skew surges $Y_i$ one can regard the tail distribution of $Y$ as that of a Generalized Pareto Distribution (GPD).

Then the tail distribution of $Z$ can be computed by convolution.

Mind that this package is quite old since it was created during the pre-RStudio era.

SeaLev Guide

The package does not have any vignette as such, yet the SeaLev Package guide available here is shipped with the package as a pdf file (with extra compression).

Installation

Using the remotes package

In an R session use

library(remotes)
install_github("IRSN/SeaLev", dependencies = TRUE)

This should install the package and make it ready to use.

You can also select a specific branch or a specific commit by using the suitable syntax for install_github. For instance to install the branch develop use

install_github("IRSN/SeaLev@develop", dependencies = TRUE)

See the remotes package documentation for more details.

Clone, build and install

Cloning the repository

You can also clone the repository to install the package. If you do not have yet a local SeaLev repository, use git clone to clone the SeaLev repository

git clone https://github.com/IRSN/SeaLev

This will create a SeaLev sub-directory of the current directory, i.e. the directory from which the git command was issued. Of course this can work only if you have the authorisation to clone.

Installation

Move to the parent directory of your cloned repository and use the following command from a terminal to create a tarball source file

R CMD build SeaLev

This will produce a source tarball SeaLev_x.y.z where x, y and z stand for the major, minor and patch version numbers. Then you can install from a command line

R CMD INSTALL SeaLev_x.y.z

Note that you must also have all the packages required by SeaLev installed.

You can also use the RStudio IDE to install the package.