R: Add Axis Labels to an Existing Map

mapAxis {oce} | R Documentation

## Add Axis Labels to an Existing Map

### Description

Plot axis labels on an existing map. This is an advanced function, requiring coordination with `mapPlot()` and (possibly) also with `mapGrid()`, and so it is best avoided by novices, who may be satisfied with the defaults used by `mapPlot()`.

### Usage

    mapAxis(
      side = 1:2,
      longitude = TRUE,
      latitude = TRUE,
      axisStyle = 1,
      tick = TRUE,
      line = NA,
      pos = NA,
      outer = FALSE,
      font = NA,
      lty = "solid",
      lwd = 1,
      lwd.ticks = lwd,
      col = NULL,
      col.ticks = NULL,
      hadj = NA,
      padj = NA,
      tcl = -0.3,
      cex.axis = 1,
      mgp = c(0, 0.5, 0),
      debug = getOption("oceDebug")
    )

### Arguments

`side` | the side at which labels are to be drawn. If not provided, sides 1 and 2 will be used (i.e. bottom and left-hand sides).
`longitude` | either a logical value or a numeric vector of longitudes. There are three possible cases: (1) If `longitude=TRUE` (the default) then ticks and nearby numbers will occur at the longitude grid established by the previous call to `mapPlot()`; (2) if `longitude=FALSE` then no longitude ticks or numbers are drawn; (3) if `longitude` is a vector of numerical values, then those ticks are placed at those values, and numbers are written beside them. Note that in cases 1 and 3, efforts are made to avoid overdrawing text, so some longitude values might get ticks but not numbers. To get ticks but not numbers, set `cex.axis=0`.
`latitude` | similar to `longitude` but for latitude.
`axisStyle` | an integer specifying the style of labels for the numbers on axes. The choices are: 1 for signed numbers without additional labels; 2 (the default) for unsigned numbers followed by letters indicating the hemisphere; 3 for signed numbers followed by a degree sign; 4 for unsigned numbers followed by a degree sign; and 5 for signed numbers followed by a degree sign and letters indicating the hemisphere.
`tick` | parameter passed to `axis()`.
`line` | parameter passed to `axis()`.
`pos` | parameter passed to `axis()`.
`outer` | parameter passed to `axis()`.
`font` | axis font, passed to `axis()`.
`lty` | axis line type, passed to `axis()`.
`lwd` | axis line width, passed to `axis()`).
`lwd.ticks` | tick line width, passed to `axis()`.
`col` | axis color, passed to `axis()`.
`col.ticks` | axis tick color, passed to `axis()`.
`hadj` | an argument that is transmitted to `axis()`.
`padj` | an argument that is transmitted to `axis()`.
`tcl` | axis-tick size (see `par()`).
`cex.axis` | axis-label expansion factor (see `par()`); set to 0 to prevent numbers from being placed in axes.
`mgp` | three-element numerical vector describing axis-label placement (see `par()`). It usually makes sense to set the first and third elements to zero.
`debug` | a flag that turns on debugging. Set to 1 to get a moderate amount of debugging information, or to 2 to get more.

### Author(s)

Dan Kelley

### See Also

A map must first have been created with `mapPlot()`.

Other functions related to maps: `formatPosition()`, `lonlat2map()`, `lonlat2utm()`, `map2lonlat()`, `mapArrows()`, `mapContour()`, `mapCoordinateSystem()`, `mapDirectionField()`, `mapGrid()`, `mapImage()`, `mapLines()`, `mapLocator()`, `mapLongitudeLatitudeXY()`, `mapPlot()`, `mapPoints()`, `mapPolygon()`, `mapScalebar()`, `mapText()`, `mapTissot()`, `oceCRS()`, `shiftLongitude()`, `usrLonLat()`, `utm2lonlat()`

### Examples

    library(oce)
    data(coastlineWorld)
    par(mar=c(2, 2, 1, 1))
    lonlim <- c(-180, 180)
    latlim <- c(70, 110)
    # In mapPlot() call, note axes and grid args, to
    # prevent over-plotting of defaults.  Some adjustments
    # might be required to the mapGrid() arguments, to
    # get agreement with the axis. This is why both
    # mapGrid() and mapAxis() are best avoided; it is
    # simpler to let mapPlot() handle these things.
    mapPlot(coastlineWorld, projection="+proj=stere +lat_0=90",
            longitudelim=lonlim, latitudelim=latlim,
            col="tan", axes=FALSE, grid=FALSE)
    mapGrid(15, 15)
    mapAxis(axisStyle=5)

[Package oce version 1.7-2 Index]