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”.
map2lonlat(x, y, init = NULL, debug = getOption("oceDebug"))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.
vector containing the y coordinate of points in the projected space
(ignored if x is a list, as described above).
vector containing the initial guesses for longitude and latitude, presently ignored.
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.
A list containing longitude and latitude, with NA
values indicating points that are off the globe as displayed.
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.
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(),
oceProject(),
shiftLongitude(),
usrLonLat(),
utm2lonlat()
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)
#> $longitude
#> [1] -64.49657
#>
#> $latitude
#> [1] 45.33462
#>