Remove EPSG codes that aren't in the PROJ database
walkerke opened this issue · 1 comments
walkerke commented
In data pre-processing EPSG codes (e.g. 9300, the MML07 Grid) should be removed if they aren't found in the PROJ database (and in turn can't easily be used in R). Or, alternatively they can be kept in but filtered out by default so users only get them as options if they really want them. For example:
library(sf)
library(crsuggest)
london <- st_read("https://skgrange.github.io/www/data/london_boroughs.json")
suggest_crs(london)# A tibble: 10 x 6
crs_code crs_name crs_type crs_gcs crs_units crs_proj4
<chr> <chr> <chr> <dbl> <chr> <chr>
1 9373 MML07 Grid projected 9372 NA NA
2 9300 HS2 Survey Grid projected 9299 NA NA
3 27700 OSGB36 / British… projected 4277 m +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.99960…
4 5643 ED50 / SPBA LCC projected 4230 m +proj=lcc +lat_0=48 +lon_0=10 +lat_1=52.66…
5 3035 ETRS89-extended … projected 4258 m +proj=laea +lat_0=52 +lon_0=10 +x_0=432100…
6 3034 ETRS89-extended … projected 4258 m +proj=lcc +lat_0=52 +lon_0=10 +lat_1=35 +l…
7 32630 WGS 84 / UTM zon… projected 4326 m +proj=utm +zone=30 +datum=WGS84 +units=m +…
8 32430 WGS 72BE / UTM z… projected 4324 m +proj=utm +zone=30 +ellps=WGS72 +towgs84=0…
9 32230 WGS 72 / UTM zon… projected 4322 m +proj=utm +zone=30 +ellps=WGS72 +towgs84=0…
10 32631 WGS 84 / UTM zon… projected 4326 m +proj=utm +zone=31 +datum=WGS84 +units=m +…
EPSG code 27700 makes sense for the top choice for London and even though the others technically are suitable they aren't directly usable for most R users. Perhaps something like a drop_na argument that defaults to TRUE and removes the CRSs that aren't directly usable, but allows users to look them up if doing so intentionally.
walkerke commented
In the dev version, we now get:
> suggest_crs(london)
# A tibble: 10 x 6
crs_code crs_name crs_type crs_gcs crs_units crs_proj4
<chr> <chr> <chr> <dbl> <chr> <chr>
1 27700 OSGB36 / British… projected 4277 m +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.99960…
2 5643 ED50 / SPBA LCC projected 4230 m +proj=lcc +lat_0=48 +lon_0=10 +lat_1=52.66…
3 3035 ETRS89-extended … projected 4258 m +proj=laea +lat_0=52 +lon_0=10 +x_0=432100…
4 3034 ETRS89-extended … projected 4258 m +proj=lcc +lat_0=52 +lon_0=10 +lat_1=35 +l…
5 32630 WGS 84 / UTM zon… projected 4326 m +proj=utm +zone=30 +datum=WGS84 +units=m +…
6 32430 WGS 72BE / UTM z… projected 4324 m +proj=utm +zone=30 +ellps=WGS72 +towgs84=0…
7 32230 WGS 72 / UTM zon… projected 4322 m +proj=utm +zone=30 +ellps=WGS72 +towgs84=0…
8 32631 WGS 84 / UTM zon… projected 4326 m +proj=utm +zone=31 +datum=WGS84 +units=m +…
9 32431 WGS 72BE / UTM z… projected 4324 m +proj=utm +zone=31 +ellps=WGS72 +towgs84=0…
10 32231 WGS 72 / UTM zon… projected 4322 m +proj=utm +zone=31 +ellps=WGS72 +towgs84=0…