convert: Convert the Format of "coords" and "waypoints" Objects

Description

Convert the format of objects of class "coords" or "waypoints" between (i) decimal degrees, (ii) degrees and minutes, and (iii) degrees, minutes and seconds.

Usage

convert(x, ...)
# S3 method for coords
convert(x, fmt, ...)
# S3 method for waypoints
convert(x, fmt, ...)

Value

The original argument x, an object of class "coords" or "waypoints" with values converted as described under details and a revised "fmt" attribute reflecting the new format.

Arguments

x: object of class "coords" created by function as_coords(), or class "waypoints" created by function as_waypoints().
...: further arguments passed to or from other methods.
fmt: integer, 1L, 2L or 3L, specifying the required coordinate format.

Details

The fmt argument should be 1L to convert to decimal degrees, 2L, to convert to degrees and minutes, and 3L to convert to degrees, minutes and seconds. On conversion of a "coords" object, the original argument x is modified to 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.

Prior to conversion, the "coords" or "waypoints" object to be converted is checked to ensure its values represent valid geographic locations as described under validate().

Examples

Run this code

## Continuing example from `as_coords()`...
# \dontshow{
   dm <-
       c(5130.4659, 4932.7726, 4806.4339, 3853.3696, 0.0000, -3706.7044, -5306.2869, -2514.4093,
       -007.6754, 1823.9137, -12246.7203, -7702.1145, 0.0000, -1217.3178, 7331.0370, -5731.1536)
   names(dm) <- 
       rep(c("Nelson's Column", "Ostravice", "Tally Ho", "Washington Monument", "Null Island",
             "Tristan da Cunha", "Mawson Peak", "Silvio Pettirossi International Airport"), 2)
   invisible(as_coords(dm, fmt = 2))
   latlon(dm) <- rep(c(TRUE, FALSE), each = 8)
# }

## Named "coords" object in degrees and minutes with
## eight values each of latitude and longitude
dm

## Convert to degrees, minutes and seconds (fmt = 3)
convert(dm, 3)

## Convert to decimal degrees (fmt = 1)
convert(dm, 1)

## Show converted values as an ordinary R numeric vector
as.numeric(dm)

###
## Continuing example from `as_waypoints()`...
# \dontshow{
   wp <- data.frame(
       name = c("Nelson's Column", "Ostravice", "Tally Ho", "Washington Monument", "Null Island",
                "Tristan da Cunha", "Mawson Peak", "Silvio Pettirossi International Airport"),
       lat = c(513027.95, 493246.36, 480626.04, 385322.18, 0, -370642.26, -530617.21, -251424.56),
       lon = c(-00740.53, 182354.82, -1224643.22, -770206.87, 0, -121719.07, 733102.22, -573109.21)
   )
   invisible(as_waypoints(wp, fmt = 3))
# }

## "waypoints" object in degrees, minutes and seconds
wp

## Convert to degrees and minutes (fmt = 2)
convert(wp, 2)

## Convert to decimal degrees (fmt = 1)
convert(wp, 1)

## Show converted values as an ordinary R data frame
as.data.frame(wp)

rm(dm, wp)