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Compute barycentric coordinates

Source: R/bary.R
fm_bary.Rd

Identify knot intervals or triangles and compute barycentric coordinates

Usage

fm_bary(...)

# S3 method for class 'fm_bary'
fm_bary(bary, ...)

# S3 method for class 'list'
fm_bary(bary, ...)

# S3 method for class 'tbl_df'
fm_bary(bary, ...)

# S3 method for class 'fm_mesh_1d'
fm_bary(mesh, loc, method = c("linear", "nearest"), restricted = FALSE, ...)

# S3 method for class 'fm_mesh_2d'
fm_bary(mesh, loc, crs = NULL, ..., max_batch_size = NULL)

Arguments

...

Arguments forwarded to sub-methods.

bary

An fm_bary object, or an object that can be converted to fm_bary.

mesh

fm_mesh_1d or fm_mesh_2d object

loc

Points for which to identify the containing interval/triangle, and corresponding barycentric coordinates. May be a vector (for 1d) or a matrix of raw coordinates, sf, or sp point information (for 2d).

method

character; method for defining the barycentric coordinates, "linear" (default) or "nearest"

restricted

logical, used for method="linear". If FALSE (default), points outside the mesh interval will be given barycentric weights less than 0 and greater than 1, according to linear extrapolation. If TRUE, the barycentric weights are clamped to the (0, 1) interval.

crs

Optional crs information for loc

max_batch_size

integer; maximum number of points to process in a single batch. This speeds up calculations by avoiding repeated large internal memory allocations and data copies. The default, NULL, uses max_batch_size = 2e5L, chosen based on empirical time measurements to give an approximately optimal runtime.

Value

A fm_bary object, a tibble with columns index; either

  • vector of triangle indices (triangle meshes),

  • matrix of interval knot indices (1D meshes), or

  • matrix of lower left box indices (2D lattices),

and where, a matrix of barycentric coordinates.

Methods (by class)

  • fm_bary(fm_bary): Returns the bary input unchanged

  • fm_bary(list): Converts a list bary to fm_bary. In the list elements are unnamed, the names index and where are assumed.

  • fm_bary(tbl_df): Converts a tibble::tibble() bary to fm_bary

  • fm_bary(fm_mesh_1d): Return an fm_bary object with elements index (edge index vector pointing to the first knot of each edge) and where (barycentric coordinates, 2-column matrices). Use fm_bary_simplex() to obtain the corresponding endpoint knot indices.

    For method = "nearest", index contains the index of the nearest mesh knot, and where is a single-column all-ones matrix.

  • fm_bary(fm_mesh_2d): An fm_bary object with columns index (vector of triangle indices) and where (3-column matrix of barycentric coordinates). Points that were not found give NA entries in index and where.

See also

fm_bary_simplex(), fm_bary_loc()

Examples

bary <- fm_bary(fm_mesh_1d(1:4), seq(0, 5, by = 0.5))
bary
#> # A tibble: 11 × 2
#>    index where[,1]  [,2]
#>  * <int>     <dbl> <dbl>
#>  1     1       2    -1  
#>  2     1       1.5  -0.5
#>  3     1       1     0  
#>  4     1       0.5   0.5
#>  5     2       1     0  
#>  6     2       0.5   0.5
#>  7     3       1     0  
#>  8     3       0.5   0.5
#>  9     3       0     1  
#> 10     3      -0.5   1.5
#> 11     3      -1     2  
str(fm_bary(fmexample$mesh, fmexample$loc_sf))
#> fm_bary [10 × 2] (S3: fm_bary/tbl_df/tbl/data.frame)
#>  $ index: int [1:10] 358 301 413 337 369 221 363 329 329 142
#>  $ where: num [1:10, 1:3] 0.0699 0.1367 0.4852 0.0831 0.6245 ...