coastline-class {oce} | R Documentation

## Class to store coastline data

### Description

Class to store coastline data, with standard slots `metadata` (containing `fillable` and `filename`), `data` (containing `longitude` and `latitude`) and `processingLog`.

### Methods

#### Extracting values

Positional data may be accessed as e.g. `coastline[["longitude"]]` or `coastline[["latitude"]]`, with abbreviations (e.g. `coastline[["lo"]]`) being permitted so long as they are distinct. However, metadata must be named in full.

#### Assigning values

Latitude may be changed with e.g. `coastline[["longitude"]] <- value`, and of course the same can be done for `latitude`.

#### Overview of contents

The `show` method (e.g. `show(coastline)`) displays information about the object.

### Data sources

The NOAA website http://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html is a popular starting point for coastline data. One assumes the data have some sort of authority, being provided by a national organization. Another source for coastline data is http://www.naturalearthdata.com, which provides world datasets in a variety of resolutions. Another advantage of the Natural Earth is that it provides data not just for coastlines, but also for rivers, lakes, glaciated areas, and place names. The `oce` dataset named `coastlineWorld` came from Natural Earth.

### Archiving your own coastline files

The present package provides a coarse-resolution world coastline in `coastlineWorld`, and the ocedata package provides two alternatives at world scale. It is common for users to want to use other coastlines, but CRAN policies do not allow packages with tens of megabytes of such data. Users should download such data and store them in `.rda` files with e.g., for a shapefile-formate file is named `"mycoastline.shp"` to be stored in a directory named `/data/coastlines`, one might do as follows.

          mycoastline <- oce::read.oce("mycoastline.shp")
          save(mycoastline, file="/data/coastlines/mycoastline.rda")
          tools::resaveRdaFiles("/data/coastlines/mycoastline.rda", compress="auto")

after which accessing the saved `mycoastline` dataset is as simple as writing

            load("/data/coastlines/mycoastline.rda")

Note: it is important to save the coastline with a new name, to avoid conflicts with `coastlineWorld` in the present package, and `coastlineWorldMedium` and `coastlineWorldFine` in the ocedata package.

### Author(s)

Dan Kelley

### See Also

Use `as.coastline` to convert data to this form, `read.coastline` to read data in various formats, and `plot.coastline` to plot coastlines.

[Package oce version 0.9-18 Index]