Converting legacy INLA mesh code to fmesher

Deprecation warnings

Three INLA::inla.getOption()/INLA::inla.setOption() options control the transition behaviour of the INLA package use of fmesher.


Great effort has been taken to preserve backwards compatibility as far as practical, with in particular the old inla.mesh, inla.mesh.1d, and inla.mesh.segment object classes given fallback methods that carry out methods for the new fm_mesh_2d, fm_mesh_1d, and fm_segm classes.

An important change is that the handling of mesh crs information is now more flexible, but stricter in the sense that user code should make no assumption about how the information is stored in the mesh, and should therefore avoid the direct mesh$crs access, and instead use the fm_crs() and fm_CRS() access methods, depending on what type of CRS object is needed. The ideal way to specify crs information is in the initial mesh creation call. If the crs needs to be explicitly assigned a new value, use the fm_crs(mesh) <- crs assignment method.

For mesh and curve creation, the fm_rcdt_2d_inla(), fm_mesh_2d_inla(), and fm_nonconvex_hull_inla() methods will keep the interface syntax used by inla.mesh.create(), inla.mesh.2d(), and inla.nonconvex.hull() functions, respectively, whereas the fm_rcdt_2d(), fm_mesh_2d(), and fm_nonconvex_hull() interfaces may change in the future.

Mesh construction

INLA fmesher
inla.mesh.create() fm_rcdt_2d() , fm_rcdt_2d_inla()
inla.mesh.2d() fm_mesh_2d() , fm_mesh_2d_inla()
inla.delaunay() fm_delaunay_2d()
inla.mesh.1d() fm_mesh_1d()
inla.mesh.lattice() fm_lattice_2d()
inla.mesh.segment() fm_segm()
inla.nonconvex.hull() fm_nonconvex_hull(), fm_extensions() , fm_simplify()
inla.nonconvex.hull() , inla.contour.segment(), inla.simplify.curve() fm_nonconvex_hull_inla(), fm_simplify_helper() , fm_segm_contour_helper()

Basis and function evaluation

INLA fmesher
inla.mesh.projector() fm_evaluator()
inla.mesh.project() fm_evaluate()
inla.spde.make.A() fm_basis() , fm_row_kron() , inlabru::bru_mapper_multi() , inlabru::ibm_jacobian(), fm_block() , fm_block_eval() , inlabru::bru_mapper_aggregate()
inla.mesh.deriv() fm_basis()

Finite element methods

INLA fmesher Comment
inla.mesh.fem() , inla.mesh.1d.fem() fm_fem()
fm_matern_sample() Convenience function that combines fm_matern_precision() and fm_sample().
fm_covariance() Basic helper function for compution covariances between different locations. Can produce sparse inverses like inla.qinv(), but currently (version 0.1.1) only by a ‘brute force’ method.
fm_sample() Basic sampling method, like inla.qsample()


INLA fmesher Comments
summary.inla.mesh() print.fm_mesh_2d(), print.fm_segm() , print.fm_mesh_1d() Use print(mesh) etc.

CRS information and coordinate transformations

INLA fmesher Comments
inla.spTransform() fm_transform()
mesh$crs fm_crs(mesh) , fm_CRS(mesh) The crs may now be stored in different formats; use fm_crs() for sf format, and fm_CRS() for sp format. fmesher will attempt to convert when needed.
mesh$crs<- fm_crs(mesh)<- Direct assignment of crs information should be avoided, but is allowed as long as its compatible with the actual mesh coordinates.


INLA fmesher Comment
No ggplot support geom_fm(data = mesh), geom_fm(data = segm) Use ggplot() + geom_fm(data = mesh) and inlabru::gg() methods
plot.inla.mesh(rgl = FALSE) plot.fm_mesh_2d() , lines.fm_mesh_2d() Use plot() or lines()
lines.inla.mesh.segment(rgl = FALSE) plot.fm_segm() , lines.fm_segm() Use plot() or lines()
plot.inla.mesh(rgl = TRUE) plot_rgl() , lines_rgl()
lines.inla.mesh.segment(rgl = TRUE) plot_rgl() , lines_rgl()