I have a shapefile of US counties downloaded from the Census, a set of points, and a calculated radius around each point. I'm trying to draw a circle of that radius around each point, then plot the overlap and do various calculations on that overlap.
The calculations come later, but right now, when I run the following code, I get an error. Here is a reproducible example:
library(sf) library(tidyverse) library(USAboundaries) albers_epsg <- 42303 # 102003 # download county boundaries counties <- us_counties(map_date = "2000-01-01", resolution = "high", states = c("Utah", "New Mexico", "Colorado", "Arizona")) st_crs(counties) plot(st_geometry(counties)) counties <- counties %>% st_transform(albers_epsg) # initialize point and project latitude and longitude to a coordinate system # that prioritizes accurate distances lon <- -111.101099 lat <- 40.477140 elev <- 150 tower <- st_point(x = c(lon, lat, elev), dim = "XYZ") tower <- tower %>% st_sfc(crs = st_crs(counties)$epsg) %>% st_transform(albers_epsg) # draw the radio horizon around the tower scalar <- 3.57 radius <- scalar * sqrt(tower[]) * 1000 tower_buffer <- st_buffer(tower, dist = radius) plot(st_geometry(st_intersection(counties, tower_buffer)))
I understand that I have to project the latitude/longitude points from EPSG 4326 (which is how the shapefiles come from the Census) into a form that can measure distance. I care about accurate distance most of all, so I chose the Albers, which is EPSG 102003 or EPSG 42303.
When I run the code above, however, I get this error:
Error in CPL_transform(x, crs$proj4string) : OGR error In addition: Warning message: In CPL_crs_from_epsg(as.integer(x)) : GDAL Error 6: EPSG PCS/GCS code 42303 not found in EPSG support files. Is this a valid EPSG coordinate system?
The error is the same if I use EPSG 102003 instead. Does R not support these projections? I'm using R 3.5.1 that I built from source on a Debian 9 machine.