plot.coastline {oce}R Documentation

Plot a coastline

Description

Plot a coastline

Usage

## S4 method for signature 'coastline'
plot(x,
     xlab="", ylab="", showHemi=TRUE,
     asp,
     clongitude, clatitude, span,
     lonlabel=NULL, latlabel=NULL, sides=NULL,
     projection=NULL,
     expand=1,
     mgp=getOption("oceMgp"), 
     mar=c(mgp[1]+1,mgp[1]+1,1,1),
     bg,
     fill, # just so we catch it's use ... will be removed at some later time
     border=NULL, col="lightgray",
     axes=TRUE, cex.axis=par('cex.axis'),
     add=FALSE, inset=FALSE,
     geographical=0,
     longitudelim, latitudelim,
     debug=getOption("oceDebug"),
     ...)

Arguments

x

A coastline object, as read by read.coastline or created by as.coastline, or a list containing items named longitude and latitude.

xlab

label for x axis

ylab

label for y axis

showHemi

logical indicating whether to show the hemisphere in axis tick labels.

asp

Aspect ratio for plot. The default is for plot.coastline to set the aspect ratio to give natural latitude-longitude scaling somewhere near the centre latitude on the plot. Often, it makes sense to set asp yourself, e.g. to get correct shapes at 45N, use asp=1/cos(45*pi/180). Note that the land mass is not symmetric about the equator, so to get good world views you should set asp=1 or set ylim to be symmetric about zero. Any given value of asp is ignored, if clongitude and clatitude are given.

clongitude,clatitude

optional center latitude of map, in decimal degrees. If both clongitude and clatitude are provided, then any provided value of asp is ignored, and instead the plot aspect ratio is computed based on the center latitude. If clongitude and clatitude are provided, then span must also be provided, and in this case, it is not permitted to also specify longitudelim and latitudelim.

span

optional suggested diagonal span of the plot, in kilometers. The plotted span is usually close to the suggestion, although the details depend on the plot aspect ratio and other factors, so some adjustment may be required to fine-tune a plot. A value for span must be supplied, if clongitude and clatitude are supplied.

lonlabel,latlabel,sides

optional vectors of longitude and latitude to label on the indicated sides of plot, passed to plot.coastline. Using these arguments permits reasonably simple customization. If they are are not provided, reasonable defaults will be used.

projection

optional map projection to use (see mapPlot). If set to FALSE then no projection is used, and the data are plotted in a cartesion frame, with aspect ratio set to reduce distortion near the middle of the plot. This option is useful if the coastline produces spurious horizontal lines owing to islands crossing the plot edges (a problem that plagues map projections). If projection is not set, a Mercator projection is used for latitudes below about 70 degrees, as if projection="+proj=merc" had been supplied, or a Stereopoloar one is used as if projection="+proj=stere". Otherwise, projection must be a character string identifying a projection accepted by mapPlot.

expand

numerical factor for the expansion of plot limits, showing area outside the plot, e.g. if showing a ship track as a coastline, and then an actual coastline to show the ocean boundary. The value of expand is ignored if either xlim or ylim is given.

mgp

3-element numerical vector to use for par(mgp), and also for par(mar), computed from this. The default is tighter than the R default, in order to use more space for the data and less for the axes.

mar

value to be used with par("mar").

bg

optional colour to be used for the background of the map. This comes in handy for drawing insets (see “details”).

fill

a legacy parameter that will be permitted only temporarily; see “History”.

border

colour of coastlines and international borders (passed to polygon, which does the drawing).

col

the colour with which to fill (passed to polygon, which does the drawing.) This is ignored unless the coastline object is fillable.

axes

boolean, set to TRUE to plot axes.

cex.axis

value for axis font size factor.

add

boolean, set to TRUE to draw the coastline on an existing plot. Note that this retains the aspect ratio of that existing plot, so it is important to set that correctly, e.g. with asp=1/cos(lat * pi / 180), where clat is the central latitude of the plot.

inset

set to TRUE for use within plotInset. The effect is to prevent the present function from adjusting margins, which is necessary because margin adjustment is the basis for the method used by plotInset.

geographical

flag indicating the style of axes. If geographical=0, the axes are conventional, with decimal degrees as the unit, and negative signs indicating the southern and western hemispheres. If geographical=1, the signs are dropped, with axis values being in decreasing order within the southern and western hemispheres. If geographical=2, the signs are dropped and the axes are labelled with degrees, minutes and seconds, as appropriate.

longitudelim

this and latitudelim provide a second way to suggest plot ranges. Note that these may not be supplied if clongitude, clatitude and span are given.

latitudelim

see longitudelim.

debug

set to TRUE to get debugging information during processing.

...

optional arguments passed to plotting functions. For example, set yaxp=c(-90,90,4) for a plot extending from pole to pole.

Details

This function plots a coastline. An attempt is made to fill the space of the plot, and this is done by limiting either the longitude range or the latitude range, as appropriate, by modifying the eastern or northern limit, as appropriate.

To get an inset map inside another map, draw the first map, do par(new=TRUE), and then call plot.coastline with a value of mar that moves the inset plot to a desired location on the existing plot, and with bg="white".

Value

None.

History

Until February, 2016, plot.coastline relied on a now-defunct argument fill to control colours; col is to be used now, instead. Also, in February, 2016, the arguments named parameters and orientation were both removed, as they had become nonfunctional about a year previously, in the transition to using rgdal to carry out map projections.

Author(s)

Dan Kelley

See Also

The documentation for coastline-class explains the structure of coastline objects, and also outlines the other functions dealing with them.

Examples

## Not run: 
library(oce)
par(mar=c(2, 2, 1, 1))
data(coastlineWorld)
plot(coastlineWorld)
plot(coastlineWorld, clongitude=-63.6, clatitude=44.6, span=1000)

## Canada in Lambert projection
plot(coastlineWorld, clongitude=-95, clatitude=65, span=5500,
     grid=10, projection='+proj=laea +lon_0=-100 +lat_0=55')

## End(Not run)

[Package oce version 0.9-18 Index]