Get the 2km grid reference

This function returns the 2km grid reference for a higher precision grid reference.

tetrad(x)

# S3 method for gridref
tetrad(grid_reference)

Arguments

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

Value

The grid reference at 2km resolution.

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

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

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 two_km column
suppressPackageStartupMessages({
  suppressWarnings({
    library(dplyr)
  })
})

grid_references %>%
  rowwise() %>%
  mutate(two_km = tetrad(grid_reference))
#> # A tibble: 15 x 2
#> # Rowwise: 
#>    grid_reference two_km
#>    <gridref>      <chr> 
#>  1 TL2384         TL28H 
#>  2 TL232839       TL28G 
#>  3 TL2385         TL28H 
#>  4 TL231840       TL28H 
#>  5 TL232839       TL28G 
#>  6 TL23248346     TL28G 
#>  7 TL23568493     TL28H 
#>  8 TL23448505     TL28H 
#>  9 TL23128324     TL28G 
#> 10 TL234850       TL28H 
#> 11 TL234846       TL28H 
#> 12 TL232839       TL28G 
#> 13 TL231841       TL28H 
#> 14 TL226846       TL28H 
#> 15 TL2384         TL28H