st_coordinates()
sf
inla()
spde <- inla.spde2.matern(mesh = mesh, alpha = 2, constr = TRUE)
indexs <- inla.spde.make.index("s", spde$n.spde) > str(indexs) List of 3 $ s : int [1:3747] 1 2 3 4 5 6 7 8 9 10 ... $ s.group: int [1:3747] 1 1 1 1 1 1 1 1 1 1 ... $ s.repl : int [1:3747] 1 1 1 1 1 1 1 1 1 1 ...