geoTrans: Manipulate Geographical Coordinates

Description

geoTrans transforms geographical coordinates in degrees, minutes and seconds input as characters (or a factor) into numerical values in degrees. geoTrans2 does the reverse operation.

Usage

geoTrans(x, degsym = NULL, minsym = "'", secsym = "\"")
geoTrans2(lon, lat = NULL, degsym = NULL, minsym = "'",
          secsym = "\"", dropzero = FALSE, digits = 3,
          latex = FALSE)

Value

geoTrans returns a numeric vector with the coordinates in degrees (eventually as decimal values). geoTrans2 returns a character vector.

Arguments

x: a vector of character strings storing geographical coordinates; this can be a factor with the levels correctly set.
degsym, minsym, secsym: a single character giving the symbol used for degrees, minutes and seconds, respectively.
lon: either a vector of numeric values with the longitudes in degrees, or, if lat = NULL, a matrix (or a data frame) giving the longitudes in the first column and the latitudes in the second column.
lat: a vector with the latitudes.
dropzero: a logical value: if TRUE, the number of arc-seconds is dropped if it is zero; similarly for the number of arc-minutes if the number of arc-seconds is also zero.
digits: an integer used for rounding the number of arc-seconds.
latex: a logical value: if TRUE, the returned character is formatted with LaTeX code.

Author

Emmanuel Paradis

Details

geoTrans should be robust to any pattern of spacing around the values and the symbols (see examples). If the letter S, W, or O is found is the coordinate, the returned value is negative. Note that longitude and latitude should not be mixed in the same character strings.

geoTrans2 can be used with cat (see examples).

The default for degsym (NULL) is because the degree symbol (°) is coded differently in different character encodings. By default, the function will use the appropriate character depending on the system and encoding used.

Examples

Run this code

coord <- c("N 43°27'30\"", "N43°27'30\"", "43°27'30\"N",
           "43° 27' 30\" N", "43 ° 27 ' 30 \" N",
           "43°27'30\"", "43°27.5'")
cat(coord, sep = "\n")
geoTrans(coord)
geoTrans("43 D 27.5'", degsym = "D")
geoTrans("43° 27' 30\" S")

XL <- c(100.6417, 102.9500)
YL <- c(11.55833, 14.51667)
cat(geoTrans2(XL, YL, dropzero = TRUE), sep = "\n")
cat(geoTrans2(XL, YL, latex = TRUE), sep = "\\\n")

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