Get compactness

Calculate shape compactness (Miller's index).

Usage

get_compactness(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 numeric scalar

• If x is a list: returns a numeric vector

• If x is a tibble: returns a numeric vector extracted from coo column

Details

Compactness (Miller's index) = Area / Area(bounding_box). Value of 1 for shapes that completely fill their bounding box (rectangles). Lower values indicate less compact shapes.

Note: Polsby-Popper compactness (4π × Area / Perimeter²) is available as get_circularity().

See also

get_circularity(), get_rectangularity()

Examples

get_compactness(shapes$cat)
#> [1] 0.5346923

# Use in measure()
bot %>% measure("compactness")
#> # A tibble: 40 × 4
#>    coo       type   dummy coo_compactness
#>    <out>     <fct>  <fct>           <dbl>
#>  1 (138 x 2) whisky a               0.762
#>  2 (168 x 2) whisky a               0.775
#>  3 (189 x 2) whisky a               0.765
#>  4 (129 x 2) whisky a               0.793
#>  5 (152 x 2) whisky a               0.652
#>  6 (161 x 2) whisky a               0.784
#>  7 (124 x 2) whisky a               0.808
#>  8 (126 x 2) whisky a               0.766
#>  9 (183 x 2) whisky a               0.763
#> 10 (193 x 2) whisky a               0.785
#> # ℹ 30 more rows