Skip to contents

Cut outline at landmarks

Source: R/get.R
get_cut.Rd

Split an outline into open curves at landmark positions.

Usage

get_cut(x, ldk = NULL, ..., .cols = NULL, .ldk_col = NULL)

Arguments

x

A matrix (nx2), list of matrices, or tibble with coo columns.

ldk

Integer vector. Landmark indices to cut at. Required for single matrix.

...

Additional arguments (reserved for future use).

.cols

Column name(s) to process when x is a tibble. If NULL, automatically detects columns containing coo columns.

.ldk_col

Character. Name of landmark column. If NULL, uses colname_ldk.

Value

  • If x is a single matrix: returns a list of matrices (open curves with class 'cur')

  • If x is a list: returns a list of lists (one per shape)

  • If x is a tibble: returns a tibble with _cur1, _cur2, etc. columns

Details

Splits an outline into segments between consecutive landmarks. Each segment is an open curve that starts and ends at landmarks.

For an outline with landmarks at positions 3 and 7 (8 points total):

  • Curve 1: points 3→4→5→6→7

  • Curve 2: points 7→8→1→2→3 (wraps around)

Requires at least 2 landmarks. Landmarks are included at the start and end of each curve.

See also

get_join()

Examples

# Cut outline at landmarks
coo <- matrix(1:20, ncol=2)
get_cut(coo, ldk = c(3, 7))
#> [[1]]
#>      [,1] [,2]
#> [1,]    3   13
#> [2,]    4   14
#> [3,]    5   15
#> [4,]    6   16
#> [5,]    7   17
#> attr(,"class")
#> [1] "cur"    "matrix"
#> 
#> [[2]]
#>      [,1] [,2]
#> [1,]    7   17
#> [2,]    8   18
#> [3,]    9   19
#> [4,]   10   20
#> [5,]    1   11
#> [6,]    2   12
#> [7,]    3   13
#> attr(,"class")
#> [1] "cur"    "matrix"
#>