Clip a grid to a shapefile but keep cells whole

Question

I have two shapefiles: One Hexagonal Grid, One Bounding Shapefile:

I am trying to clip the Grid to the Shapefile BUT no matter how I try st_intersect(), st_overlap(), st_contains(), etc, the result is always the same:

What I want is to clip the Grid and keep the remaining cells whole like this:

I can accomplish this in QGIS, but I am looking for a solution in R. Thanks!

Answer 1

Here's one way:

library(sf)
library(tidyverse)


# example data
# using the state border of north carolina
nc = st_read(system.file("shape/nc.shp", package="sf")) %>%
  st_union()

# create a bounding box
bbox <- st_bbox(nc) %>% st_as_sfc()

# make a hexagonal grid over the bounding box
hex_grid <- st_make_grid(bbox, square = FALSE, n = 40)  
hex_sf <- hex_grid %>% st_as_sf()

#index of hexagons fully or partially covered by the state
intersections_index <- st_intersects(nc, hex_grid, sparse = F)

# sf object of only the hexagons we want
intersected_hex <- hex_sf[intersections_index, ]

## plotting it all:
ggplot() + 
  geom_sf(data = hex_sf, color = 'orange') +
  geom_sf(data = intersected_hex, fill = 'gray40')+
  geom_sf(data = nc, color = 'blue', fill = NA) 

Full hexagonal grid in orange, selected hexagons in gray, state outline (bounding shapefile) in blue.

^{Created on 2023-01-18 by the reprex package (v2.0.1)}