How to create thiessen polygons from points using R packages?

Question

I have multiple sets of points (for different years ~20)

I want to generate thiessen polygons for each set of points using r spatial packages.

I know this c

Answer 1

Note that Voronoi cells are also known as Thiessen polygons.

Alternatively, one can make use of the Simple Features for R, specifically, the sf::st_voronoi() function. Below are examples inspired from this help page:

library(sf)
#> Linking to GEOS 3.8.0, GDAL 3.0.4, PROJ 6.3.1

# generate some random points
set.seed(2020-05-27)
n <- 50
points <- runif(n) %>% 
  matrix(ncol = 2) %>% 
  st_multipoint()

# Voronoi tesselation
voronoi_grid <- st_voronoi(points)

plot(voronoi_grid, col = NA)
plot(points, add = TRUE, col = "blue", pch = 16)

^{Created on 2020-05-27 by the reprex package (v0.3.0)}

Since you mentioned that you have multiple sets of points, one set for a year, you can make use of lists and iterate over them, for example:

library(sf)
#> Linking to GEOS 3.8.0, GDAL 3.0.4, PROJ 6.3.1

# generate a list of length 20, each element containing with random points 
set.seed(2020-05-27)
yrs <- 20
n <- 50
points_lst <- vector(mode = "list", length = yrs)
for (i in 1:yrs) {
  points_lst[[i]] <- runif(n) %>% 
    matrix(ncol = 2) %>% 
    st_multipoint()
}

# Voronoi tesselation for each element of the list
voronoi_grids_lst <- lapply(points_lst, st_voronoi)

# plot 1st element
plot(voronoi_grids_lst[[1]], col = NA)

^{Created on 2020-05-27 by the reprex package (v0.3.0)}