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Check if Irish grid references are valid

Source: R/igr_is_valid.R
igr_is_valid.Rd

igr_is_valid() identifies valid Irish grid references.

Usage

igr_is_valid(x, tetrad = TRUE)

Arguments

x

A character vector of Irish grid references.

tetrad

Permit tetrad form of Irish grid reference?

Value

A logical vector indicating the validity of each Irish grid reference.

Details

Valid Irish grid references consist of a letter (other than I) optionally followed by both an easting and northing. The easting and northing must be of the same length of between 1 and 5 digits. There may be whitespace between the letter, easting and northing.

The tetrad form of Irish grid reference consists of a valid 10 km precision Irish grid reference (one letter, one digit easting and one digit northing) followed by a letter (other than O). This refers to a 2 km square within the 10 km square referenced.

Examples

# A vector of alternating valid and invalid Irish grid references
v <- c("N8090", "D 12 345 88800", "W34", "I30", "W", "A123", "B1234", "", "A12Z", "A12O")

# Check validity of Irish Grid coordinates
igr_is_valid(v)
#>  [1]  TRUE FALSE  TRUE FALSE  TRUE FALSE  TRUE FALSE  TRUE FALSE

# Check validity of Irish Grid coordinates, disallowing tetrad form
igr_is_valid(v, tetrad = FALSE) 
#>  [1]  TRUE FALSE  TRUE FALSE  TRUE FALSE  TRUE FALSE FALSE FALSE