Wrap coordinates from rows to list-column of matrices

Converts x and y coordinate columns into a list-column of matrices, with one matrix per group (defined by other columns or an .id column).

Usage

wrap(.data, x = x, y = y, .into = "coo", .class = "coo")

Arguments

.data

A tibble with x and y coordinate columns

x

Column name for x coordinates (unquoted). Default is x.

y

Column name for y coordinates (unquoted). Default is y.

.into

Name of the new list-column to create. Default is "coo".

.class

Character vector of classes to PREFIX to the list-column. The list-column always has base classes c("coo", "list"). If .class is provided, these classes are prepended, e.g., .class = "out" results in c("out", "coo", "list"). Individual matrices always get class c("xy", "matrix", "array") regardless of this parameter. Set to NULL for just c("coo", "list").

Value

A tibble with x and y columns removed and replaced by a list-column containing coordinate matrices (one per group). Individual matrices have class c("xy", "matrix", "array") with column names c("x", "y"). The list-column has class c(.class, "coo", "list") if .class is provided, or c("coo", "list") if .class = NULL.

Details

The function groups rows by all columns except x and y, then wraps each group's coordinates into a matrix. This is the inverse of unwrap().

Grouping behavior:

• If .data has grouping (from group_by()), uses existing groups

• If no groups, wraps ALL rows into a single matrix (assumes single shape)

• For multiple shapes, ensure you have identifying columns or use .id in unwrap()

See also

unwrap() for the reverse operation

Examples

# Start with unwrapped coordinates
df_unwrapped <- tibble::tibble(
  id = rep(1:3, each = 4),
  x = c(0, 1, 1, 0,  2, 3, 3, 2,  4, 5, 5, 4),
  y = c(0, 0, 1, 1,  0, 0, 1, 1,  0, 0, 1, 1)
)

# Wrap by id (x and y are defaults)
df_wrapped <- df_unwrapped %>% wrap()
df_wrapped
#> # A tibble: 3 × 2
#>      id coo    
#>   <int> <coo>  
#> 1     1 (4 x 2)
#> 2     2 (4 x 2)
#> 3     3 (4 x 2)
# A tibble: 3 × 2
#      id coo
#   <int> <coo>
# 1     1 (4 x 2)
# 2     2 (4 x 2)
# 3     3 (4 x 2)

# Explicit column names
df_wrapped <- df_unwrapped %>% wrap(x, y, .into = "coo")

# Individual matrices have "xy" class
df_wrapped$coo[[1]]
#> <xy [4 x 2]>
#>      x y
#> [1,] 0 0
#> [2,] 1 0
#> [3,] 1 1
#> [4,] 0 1
class(df_wrapped$coo[[1]])
#> [1] "xy"     "matrix" "array" 
# [1] "xy"     "matrix" "array"

# List-column has "coo" class
class(df_wrapped$coo)
#> [1] "coo"  "coo"  "list"
# [1] "coo"  "list"

# Prefix with "out" for outlines
df_out <- wrap(df_unwrapped, .into = "outline", .class = "out")
class(df_out$outline)
#> [1] "out"  "coo"  "list"
# [1] "out"  "coo"  "list"

# No prefix classes (just base "coo")
wrap(df_unwrapped, .class = NULL)
#> # A tibble: 3 × 2
#>      id coo    
#>   <int> <coo>  
#> 1     1 (4 x 2)
#> 2     2 (4 x 2)
#> 3     3 (4 x 2)