Spatial aggregation containing NA values with stars R package

aggregate.stars-example.R

library(stars)

# USA states
nc = sf::read_sf(system.file("gpkg/nc.gpkg", package = "sf"), "nc.gpkg")
nc = st_transform(nc, "OGC:CRS84")

# Coarse grid upon the map
bb <- as.list(round(st_bbox(nc)))
x <- seq(bb$xmin, bb$xmax)
y <- seq(bb$ymin, bb$ymax)
df <- expand.grid(x = x, y = y)
df$value = runif(nrow(df)) + 10
df$value[seq(1,nrow(df), 3)] <- NA
star <- st_as_stars(df, dims = c("x", "y"))
st_crs(star) <- st_crs(nc)

# Check the grid vs map with 
ggplot() + geom_stars(data = star) + geom_sf(data = st_geometry(nc), fill = NA)

# Spatial Aggregation
agg <- aggregate(star, st_geometry(nc), mean)
plot(agg)

# Try with coverage_fraction
agg <- aggregate(star, st_geometry(nc), mean, exact = TRUE)
plot(agg)

agg <- aggregate(star, st_geometry(nc), mean, exact = TRUE, na.rm = TRUE)
plot(agg)