Get the precision of a grid reference

This function returns the grid reference's precision in metres.

precision(x)

# S3 method for gridref
precision(grid_reference)

Arguments

grid_reference	A Great British or Irish grid reference character string with class gridref.

Value

The precision of the grid reference in metres.

Details

It can check either British or Irish grid references up to 10 figure (1m precision), including tetrads (2000m precision).

REST API

A REST API endpoint is available once a Plumber router has been created and can be requested by adding _api to the end of the function.

The API returns "" instead of NULL so that it may be used with the dplyr::mutate function. Wrap the API call with dplyr::na_if to convert "" to NA.

suppressPackageStartupMessages({
  library(store)
  suppressWarnings({
    library(plumber)
  })
})
pr("../R/gridref_api.R") %>%
  pr_run(port = 8000)

See also

The function calls the gridCoords function in the archived rnbn package.

Other grid reference functions: easting(), gridsquare_geometry(), hectad(), hectare(), monad(), northing(), pentad(), projection(), tetrad()

Examples

 suppressPackageStartupMessages({
   library(store)
   suppressWarnings({
     library(dplyr)
     library(janitor)
   })
 })

 grid_references <- nbn_demonstration_dataset %>%
   clean_names() %>%
   slice_tail(n = 15) %>%
   select(grid_reference) %>%
   mutate(grid_reference = as_gridref(grid_reference))


# add precision column
suppressPackageStartupMessages({
  suppressWarnings({
    library(dplyr)
  })
})

grid_references %>%
  rowwise() %>%
  mutate(precision = precision(grid_reference))
#> # A tibble: 15 x 2
#> # Rowwise: 
#>    grid_reference precision
#>    <gridref>          <dbl>
#>  1 TL2384              1000
#>  2 TL232839             100
#>  3 TL2385              1000
#>  4 TL231840             100
#>  5 TL232839             100
#>  6 TL23248346            10
#>  7 TL23568493            10
#>  8 TL23448505            10
#>  9 TL23128324            10
#> 10 TL234850             100
#> 11 TL234846             100
#> 12 TL232839             100
#> 13 TL231841             100
#> 14 TL226846             100
#> 15 TL2384              1000