dms_to_decimal

Convert Coordinates in Degrees, Minutes and Seconds into Decimal Degrees

barRoso::dms_to_decimal()

Description

Converts geographic coordinates written in degrees, minutes and seconds (e.g. "22º22´55´´S", "53°45'W", "12 30 15.5 S") into decimal degrees (e.g. -22.381944), as they are often recorded in herbarium labels and in the verbatim coordinates of databases like REFLORA, JABOT and speciesLink.

Details

The function recognizes:

• degree symbols º, °, ˚ or d; minute symbols ’, ´, ′, ’ or m; second symbols “, '', ´´, ″, ” or s, or just spaces between the numbers;
• decimal minutes or seconds, with dot or comma (e.g. "12°30,5'S");
• the hemisphere as N, S, E, W, or O (oeste) and L (leste) as in Portuguese and Spanish, before or after the numbers, or a minus sign;
• coordinates already in decimal degrees (e.g. "-12.5"), which are kept.

Values that cannot be converted, or with minutes or seconds of 60 or more, or out of the range of latitude (±90) or longitude (±180), are returned as NA, with a warning.

When the hemisphere is not written (e.g. "22º22´55´´"), the result is positive, unless it is given in hemisphere, e.g. hemisphere = "S" for latitudes of Brazilian specimens.

Arguments

Argument	Description
x	Character vector of coordinates.
type	Either "latitude", "longitude" or "auto" (default). It is used to check the range of the coordinates; with "auto", the range depends on the hemisphere (±90 for N and S, ±180 otherwise).
hemisphere	Optional hemisphere ("N", "S", "E" or "W") for the coordinates written without hemisphere or sign.
digits	Number of decimal places of the result (default: 6, about 10 cm).

Value

A numeric vector of coordinates in decimal degrees.

Examples

dms_to_decimal(c("22º22´55´´S", "53°45'W", "12 30 15.5 S", "S 8°30.5'", "-55.602222"))

# Latitudes without hemisphere
dms_to_decimal(c("22º22´55´´", "1º42´12´´"), type = "latitude", hemisphere = "S")

# Longitude in Portuguese (O = oeste = west)
dms_to_decimal("43º40'49''O")