map2lonlat: 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 sf::sf_project() 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.
# NOT RUN {library(oce)
## Cape Split, in the Minas Basin of the Bay of Fundycs <- list(longitude=-64.49657, latitude=45.33462)
xy <- lonlat2map(cs, projection="+proj=merc")
map2lonlat(xy)
# }