Geographic or GPS Coordinate Class

coord() creates a robust representation of a geographic or GPS cordinate based on the value of deg, min and sec, instatiated as an object of class "coord".

as_coord() converts the format of geographic or GPS coordinates between (i) decimal degrees, (ii) degrees and minutes, and (iii) degrees, minutes and seconds. It also creates "coord" objects directly from single numeric values in one of these three formats.

Usage

coord(deg, min = NULL, sec = NULL, .latorlon = c(NA, "lat", "lon"))

as_coord(object, ...)

# S3 method for class 'coord'
as_coord(object, ..., .fmt = c("decdeg", "degmin", "degminsec"))

# S3 method for class 'numeric'
as_coord(
  object,
  ...,
  .fmt = c("decdeg", "degmin", "degminsec"),
  .latorlon = c(NA, "lat", "lon")
)

# S3 method for class 'waypoint'
as_coord(object, ..., .fmt = c("decdeg", "degmin", "degminsec"))

Arguments

deg: numeric, representing the number of degrees. Must be of type integer if min or sec are provided, otherwise type double; default 0L.
min: numeric, representing the number of minutes. If sec provided, must be of type integer, otherwise double; default NULL.
sec: double, representing the number of seconds; default NULL.
.latorlon: a character string, either "lat" or "lon" indicating whether the coordinate represented is of latitude or longitude, or NA (the default).
object: a "coord" object or a numeric vector to be converted to another format.
...: further arguments passed to or from other methods.
.fmt: character string indicating the desired format; must be one of "decdeg" (default), "degmin" or "degminsec".

Value

An object of class "coord" instantiating a coordinate. Objects of "coord" class contain a list with one, two or three numeric values named "deg", "min", "sec", depending on whether the cordinate in question is represented in decimal degrees, in (integer) degrees and (decimal) minutes, or else in (integer) degrees, (integer) minutes, and (decimal) seconds.

"coord" objects have character attribute latorlon, which may be "lat" for latitude, "lon" for longitude or NA, and a logical attribute "negative", which when TRUE signifies a negative coordinate i.e., S or W, rather than N or E.

Details

The value provided in argument deg should have a decimal point after the number of whole degrees in the case of decimal degrees. Likewise, the value provided in argument min should have a decimal point after the number of whole minutes in the case of degrees and minutes, and argument deg should be of type integer. In the case of degrees, minutes and seconds, both arguments deg and min must be of type integer and argument sec should have a decimal point after the number of whole seconds.

Negative coordinates i.e., S or W, rather than N or E, may be specified by negative values of deg, min, or sec; only one, the first non-zero value, of the three may be negative or an error will result.

The total value in degrees, minutes and seconds may not be greater than 180˚, while the minutes and seconds components (if present) must be less than 60˚. If latitude is represented (i.e., latorlon attribute is "lat"), its maximum absolute value is 90˚. Errors will be reported if these limits are not observed.

as_coord() has S3 methods for both "coord" and "waypoint" objects and numeric values. Numeric values should have a decimal point after the number of whole degrees in the case of decimal degrees, after the number of whole minutes in the case of degrees and minutes, and after the number of whole seconds in the case of degrees, minutes and seconds.

There is also an S3 method for as.numeric() for objects of class "coord", returning numeric values as described above for as_coord().

Examples