inla.over_sp_mesh {INLA}

R Documentation

Check which mesh triangles are inside a polygon

Description

Wrapper for the sp::over() method to find triangle centroids or vertices inside sp polygon objects

Usage

inla.over_sp_mesh(x, y, type = c("centroid", "vertex"), ignore.CRS = FALSE)

Arguments

x	geometry (typically a sp::SpatialPolygons() object) for the queries
y	an inla.mesh() object
type	the query type; either 'centroid' (default, for triangle centroids), or 'vertex' (for mesh vertices)
ignore.CRS	logical; whether to ignore the coordinate system information in x and y (default FALSE)

Value

A vector of triangle indices (when type is 'centroid') or vertex indices (when type is 'vertex')

Author(s)

Haakon Bakka, bakka@r-inla.org, and Finn Lindgren finn.lindgren@gmail.com

Examples

# Create a polygon and a mesh
obj <- sp::SpatialPolygons(list(Polygons(list(Polygon(rbind(
    c(0, 0),
    c(50, 0),
    c(50, 50),
    c(0, 50)
))),
ID = 1
)),
proj4string = inla.CRS("longlat_globe")
)
mesh <- inla.mesh.create(globe = 2, crs = inla.CRS("sphere"))

## 3 vertices found in the polygon
inla.over_sp_mesh(obj, mesh, type = "vertex")

## 3 triangles found in the polygon
inla.over_sp_mesh(obj, mesh)

## Multiple transformations can lead to slightly different results due to edge cases
## 4 triangles found in the polygon
inla.over_sp_mesh(obj, inla.spTransform(mesh, CRSobj = inla.CRS("mollweide_norm")), ignore.CRS = FALSE)

## Ignoring mismatching coordinate systems is rarely useful
## 20 triangles "found in" the polygon
inla.over_sp_mesh(obj, inla.spTransform(mesh, CRSobj = inla.CRS("mollweide_norm")), ignore.CRS = TRUE)

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