I am trying to find the best way of obtaining: the length of the longest line from the center of a polygon to its edge.
In the code below, I download the polygon data of the 75254 zip code located in Texas, USA. I then determine the location of its center with sf::st_centroid() and I plot the geometries using the tmap package.
# Useful packages
library(dplyr)
library(sf)
library(tigris)
library(tmap)
# Download polygon data
geo <- tigris::zctas(cb = TRUE, starts_with = "75254")
geo <- st_as_sf(geo)
# Determine the location of the polygon's center
geo_center <- st_centroid(geo)
# Plot geometries
tm_shape(geo) +
tm_polygons() +
tm_shape(geo_center) +
tm_dots(size = 0.1, col = "red")
Once again, is there an efficient way to determine the length of the line going from the center of the polygon all the way to the farthest point on the polygon's edge? In other words, how can I find the radius of the circle that perfectly circumscribes the polygon given that both the circle and the polygon have the same center? Thank you very much for your help.
I think this is what I mentioned in my question. But how do I get the value of that radius?
EDIT: I think I misunderstood you. Yes, you are right actually. I'll do it and post the answer.
EDIT 2: Well, I realize that the radius I am looking for is (in this case) half the distance between xmin and xmax. But still, I am not sure how to obtain it.