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Extract triangle centroids

Source: R/mesh.R
fm_centroids.Rd

Computes the centroids of the triangles of an fm_mesh_2d() or fm_collect() object.

Usage

fm_centroids(x, format = NULL, name = NULL, ...)

# S3 method for class 'fm_mesh_2d'
fm_centroids(x, format = NULL, name = NULL, ...)

# S3 method for class 'fm_mesh_3d'
fm_centroids(x, format = NULL, name = NULL, ...)

# S3 method for class 'fm_collect'
fm_centroids(x, format = NULL, name = NULL, ...)

Arguments

x

An fm_mesh_2d object.

format

character; "sf", "df", "sp"

name

character; If non-NULL, this overrides the default sf geometry column name. When specified, it is also used as a prefix for the names of augmentation variables.

...

Further arguments passed to methods

Value

An sf, data.frame, or SpatialPointsDataFrame object, with the vertex coordinates, and a .triangle column with the triangle indices.

Methods (by class)

  • fm_centroids(fm_mesh_2d): The result is augmented with a column ".triangle"

  • fm_centroids(fm_mesh_3d): The result is augmented with a column ".tetra"

  • fm_centroids(fm_collect): The result is augmented with a column ".index" with the index of the mesh in the fm_collect object.

See also

fm_vertices()

Author

Finn Lindgren Finn.Lindgren@gmail.com

Examples

if (require("ggplot2", quietly = TRUE)) {
  vrt <- fm_centroids(fmexample$mesh, format = "sf")
  ggplot() +
    geom_sf(data = fm_as_sfc(fmexample$mesh)) +
    geom_sf(data = vrt, color = "red")
}


cen <- fm_centroids(
  fm_collect(list(fmexample$mesh, fmexample$mesh)),
  format = "sf",
  name = "xyzzy"
)
cen
#> Simple feature collection with 1094 features and 2 fields
#> Geometry type: POINT
#> Dimension:     XYZ
#> Bounding box:  xmin: -5.031762 ymin: -3.736714 xmax: 3.745673 ymax: 4.990945
#> z_range:       zmin: 0 zmax: 0
#> CRS:           NA
#> # A tibble: 1,094 × 3
#>    xyzzy.triangle xyzzy.index                      xyzzy
#>  *          <int>       <int>                    <POINT>
#>  1              1           1   Z (0.1587483 1.786677 0)
#>  2              2           1  Z (1.497639 -0.8424027 0)
#>  3              3           1  Z (0.5596638 -1.746063 0)
#>  4              4           1  Z (-3.834319 -1.845871 0)
#>  5              5           1 Z (-4.245891 -0.1659953 0)
#>  6              6           1 Z (-2.815959 -0.7159061 0)
#>  7              7           1  Z (-0.1173224 2.613329 0)
#>  8              8           1   Z (-1.383869 2.992167 0)
#>  9              9           1 Z (-2.502116 -0.7149274 0)
#> 10             10           1  Z (-2.683279 -1.960254 0)
#> # ℹ 1,084 more rows