topogeo.R

# create geometry matrix
geom <- cbind(x=c(4,4,2,5,2,3,3,3,4,2), 
              y=c(6,2,3,4,5,2,4,7,8,0))

# create data frame with special topology list column
df <- tibble::tibble(name="John", age=32, 
                     topo=list( # list column containing polygon(s) and inner/outer flag
                             list(poly = list(c(10, 5, 8, 9, 4, 2), 
                                              c(3, 6, 1, 7)),
                                  type = c(1L, 0L)))
       )

# create topogeo object which contains "shared" geometry matrix and data.frame with topologies
obj <- structure(list(geom=geom, data=df), class=c("topogeo", "list"))


plot.topogeo <- function(obj){
  plot(1, type="n", xlab="", ylab="", 
       xlim=range(obj$geom[,1]), ylim=range(obj$geom[,2]), 
       bty="n")

  add_poly <- function(topo, geom){
    for (i in seq_along(topo$poly)){
      polygon(geom[topo$poly[[i]],], col=topo$type[[i]])
    }
  }
  invisible(lapply(obj$data$topo, add_poly, obj$geom))
}


plot(obj)