README.md

In ccb60/tdggraph: Simple ggplot2 graphics for depth profiles in limnology and oceanography

tdggraph

A lightweight package to produce ggplot-based graphics from time by depth data as produced in limnology and oceanography.

Introduction

"Profile" data is common in both limnology and oceanography. Profile data is data where some sort of water quality (or more rarely, biological) parameter is measured from the water surface to depth. Often, profile data is collected at regular intervals at the same location, producing a three dimensional (time by depth by value) data set.

Common examples of time by depth data include salinity, temperature and dissolved oxygen profiles, but the general idea applies whenever a parameter is collected periodically along a vertical line.

The goal of this package is to provide a simple interface to ggplot graphics, with intelligent defaults for this type of data. In particular, profile data is usually drawn with a reversed vertical (depth) axis, so that the surface (zero depth) is at the top of the figure, with depth increasing towards the bottom. Similarly, it is common to show zero depth, even though data starts at some small depth below the water surface.

This package aims to simplify production of graphics useful in depicting these data. The package is especially useful for producing graphics from season-long series of periodic profile observations. The three main graphics functions create ggplot2 graphic objects with different strengths for emphasizing different aspects of the data. For most users, the tdsmooth() function will be the primary one of interest.

The Names

The name of the package reflects that it is intended to work with 'td' (time by depth) data, using 'gg' plot graphics.

The function names ptlines(), ptdots(), and ptsmooth() reflect that they make graphics from 'pt' (profile by time) data.

The purpose of interpol() should be obvious from its name, and the association with an international policing organization will make the name easier to remember.

The Future

The package was constructed for Casco Bay Estuary Partnership as part of the process of drafting the 2020 State of Casco Bay report (completed in 2021). Thus this version of the package should not be considered stable. Future changes are likely, and there is no intention yet of protecting backwards compatibility.

TO DO

• Develop testing suite.

• Redraft interpol() and ptsmooth() to allow selection of other smoothers.

• Evaluate alternative selection of data from the Maine DEP sonde data.

ccb60/tdggraph documentation built on Dec. 19, 2021, 1:58 p.m.