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Get bounding box corners

Source: R/get.R
get_bbox.Rd

Calculate the four corners of the bounding box.

Usage

get_bbox(x, ..., .cols = NULL)

Arguments

x

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

...

Additional arguments (reserved for future use).

.cols

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

Value

  • If x is a single matrix: returns a 4x2 matrix with corners

  • If x is a list: returns a list of 4x2 matrices

  • If x is a tibble: returns a list of 4x2 matrices extracted from coo column

Details

Returns the four corners of the axis-aligned bounding box as a 4x2 matrix:

  • Row 1: bottom-left (xmin, ymin)

  • Row 2: bottom-right (xmax, ymin)

  • Row 3: top-right (xmax, ymax)

  • Row 4: top-left (xmin, ymax)

This forms a closed rectangle suitable for plotting. This is not a scalar, so cannot be used with measure().

Examples

get_bbox(shapes$cat)
#>      x   y
#> bl 130   9
#> br 249   9
#> tr 249 231
#> tl 130 231

# Plot shape with bounding box
p(shapes$cat)
draw_outlines(list(shapes$cat))
draw_outlines(list(get_bbox(shapes$cat)), col = "red")