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Generate Irish grid references from an sf object

Source: R/st_irishgridrefs.R
st_irishgridrefs.Rd

st_irishgridrefs() returns the Irish grid references for all features in an sf object of point geometries. Features located outside the Irish Grid (EPSG:29903) extent or with empty geometry are returned as NA.

Usage

st_irishgridrefs(x, digits = 3, precision = NULL, sep = "")

Arguments

x

An sf object containing geometries of type POINT.

digits

An integer, the number of digits for both easting and northing in the Irish grid references.

  • 0: equivalent to a precision of 100 km.

  • 1: equivalent to a precision of 10 km.

  • 2: equivalent to a precision of 1 km.

  • 3 (the default): equivalent to a precision of 100 m.

  • 4: equivalent to a precision of 10 m.

  • 5: equivalent to a precision of 1 m.

precision

An integer, the precision of the Irish grid references in metres: 1, 10, 100, 1000, 2000, 10000, or 100000. Overrides digits. Use 2000 to produce the tetrad form of Irish grid reference.

sep

A character string to place between the 100 km grid letter, easting, northing, and tetrad.

Value

A character vector of Irish grid references.

Examples

# An sf object containing point data
x_sf <- sf::st_as_sf(data.frame(x = c(0, 490000), y = c(400000, 0)),
  crs = 29903,
  coords = c("x", "y")
)

# Convert to Irish grid references
st_irishgridrefs(x_sf)
#> [1] "A000000" "Z900000"

# Convert into Irish grid references with 4 digit easting and northing (10 m precision)
st_irishgridrefs(x_sf, digits = 4)
#> [1] "A00000000" "Z90000000"

# Convert into Irish grid references with 1 km precision (2 digit easting and northing)
st_irishgridrefs(x_sf, precision = 1000)
#> [1] "A0000" "Z9000"

# Convert into Irish grid references with 2 km precision (tetrad form)
st_irishgridrefs(x_sf, precision = 2000)
#> [1] "A00A" "Z90A"

# Insert a space between the 100 km grid letter, easting, and northing
st_irishgridrefs(x_sf, sep = " ")
#> [1] "A 000 000" "Z 900 000"