R: Convert X and Y to Longitude and Latitude

map2lonlat {oce} | R Documentation

## Convert X and Y to Longitude and Latitude

### Description

Convert from x-y coordinates to longitude and latitude. This is normally called internally within oce; see ‘Bugs’. A projection must already have been set up, by a call to `mapPlot()` or `lonlat2map()`. It should be noted that not all projections are handled well; see ‘Bugs’.

### Usage

    map2lonlat(x, y, init = NULL, debug = getOption("oceDebug"))

### Arguments

`x` | vector containing the x component of points in the projected space, or a list containing items named `x` and `y`, in which case the next argument is ignored.
`y` | vector containing the y coordinate of points in the projected space (ignored if `x` is a list, as described above).
`init` | vector containing the initial guesses for longitude and latitude, presently ignored.
`debug` | an integer specifying whether debugging information is to be printed during the processing. This is a general parameter that is used by many `oce` functions. Generally, setting `debug=0` turns off the printing, while higher values suggest that more information be printed. If one function calls another, it usually reduces the value of `debug` first, so that a user can often obtain deeper debugging by specifying higher `debug` values.

### Value

A list containing `longitude` and `latitude`, with `NA` values indicating points that are off the globe as displayed.

### Bugs

`oce` uses the `sf::sf_project()` function to handle projections. Only those projections that have inverses are permitted within `oce`, and of that subset, some are omitted because the `oce` developers have experienced problems with them.

### Author(s)

Dan Kelley

### See Also

`lonlat2map()` does the inverse operation.

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

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

### Examples

    library(oce)
    ## Cape Split, in the Minas Basin of the Bay of Fundy
    cs <- list(longitude=-64.49657, latitude=45.33462)
    xy <- lonlat2map(cs, projection="+proj=merc")
    map2lonlat(xy)

[Package oce version 1.7-2 Index]