Function reference • ggOceanMaps

Basemap functions

Maps are plotted using the basemap() or qmap() functions that work almost similarly to ggplot() as a base for adding further layers to the plot using the + operator. The maps generated this way already contain multiple ggplot layers. Consequently, the data argument needs to be explicitly specified inside geom_* functions when adding ggplot2 layers. Depending on the location of the map, the underlying coordinates may be projected. Decimal degree coordinates need to be transformed to the projected coordinates using the transform_coord, ggspatial, or geom_sf functions.. The shapefile_list function can be used to acquire shapefiles argument names when limiting basemaps using projected coordinates.

basemap(): Create a ggplot2 basemap for plotting variables

qmap(): Quick map

transform_coord(): Transform spatial coordinates to another projection

shapefile_list(): A list of pre-made shapefiles for basemap

dist2land(): Calculate distance to the closest land for coordinates

get_depth(): Extract depth for coordinates from a raster bathymetry dataset

Functions to help customizing basemaps

These functions help in customizing basemaps. The auto_limits function can be used to retrieve projected coordinates from decimal degree position data and the reorder_layers can be used to move land and glaciers on top of added ggplot2 data layers.

auto_limits(): Automatic limits for basemap

reorder_layers(): Move basemap land, glacier and grid layers on top of other ggplot layers

theme_map(): A ggplot2 theme for maps

Create bathymetries and shapefiles

Custom bathymetry shapes can be added using the raster_bathymetry and vector_bathymetry functions in this order. The underlying data can be retrieved from the ETOPO or GEBCO repositories. Already existing Geonorge bathymetries can be opened and added to the shapefiles argument as list(bathy =). The clip_shapefile function can be used to crop already existing SpatialPolygons.

raster_bathymetry(): Simplify a bathymetry raster ready for vectorization

vector_bathymetry(): Create a polygon bathymetry from a raster bathymetry file

geonorge_bathymetry(): Open Geonorge bathymetry shapefiles

clip_shapefile(): Clip a shapefile using a bounding area

rotate_crs(): Rotate CRS

Size adjustment functions

These functions convert line widths and font sizes measured in points (pt) to ggplot2 equivalents. They can be used to follow line width and font size requirements set by journals.

LS(): Convert line sizes measured as points to ggplot line sizes

FS(): Convert font sizes measured as points to ggplot font sizes

Map data

Shape- and raster files used by the package. Higher resolution files are stored in the ggOceanMapsLargeData repository. These files are automatically used by the basemap function. The basemap function also supports custom sf and stars objects.

dd_land: Decimal degree land shapes

dd_rbathy: Decimal degree bathymetry

Datasets

The package contains ICES and Norwegian Directorate of Fisheries areas as sf objects. These shapefiles are used in examples and included here for convenience because they are regularly needed by the package author.

ices_areas: ICES Advisory Areas

fdir_main_areas: Major fisheries areas (hovedomraade) of Norway

fdir_sub_areas: Norwegian sub-areas (lokasjon) for commercial fishing

Internal basemap functions

Internal functions dealing with data and graphics for basemap. These functions are run on the background and only needed if you modify your maps beyond the options offered by ggOceanMaps.

basemap_data(): Create basemapData object for basemap plotting

define_shapefiles(): Define a shapefile to use in plotting from the limits argument

guess_coordinate_columns(): Guess longitude and latitude columns in a data frame

is_decimal_limit(): Test whether a limit argument is specified as decimal degrees.

map_cmd(): Return map elements for basemap

round_any(): Round to multiple of any number

quiet(): Return function output quietly

dd_to_deg(): Convert decimal degree values to angular degrees

deg_to_dd(): Convert angular degrees to decimal degree values

select_element(): Select an element of each vector from a list

dd_clip_boundary(): Create clip boundary from decimal degree limits