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Get convexity

Source: R/get.R
get_convexity.Rd

Calculate convexity as the ratio of convex hull perimeter to shape perimeter.

Usage

get_convexity(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

Convexity = Perimeter(convex_hull) / Perimeter(shape). Value of 1 for convex shapes. Lower values indicate concavities.

See also

get_solidity(), get_chull()

Examples

get_convexity(shapes$cat)
#> [1] 0.7305908

# Use in measure()
bot %>% measure("convexity")
#> # A tibble: 40 × 4
#>    coo       type   dummy coo_convexity
#>    <out>     <fct>  <fct>         <dbl>
#>  1 (138 x 2) whisky a             0.991
#>  2 (168 x 2) whisky a             0.990
#>  3 (189 x 2) whisky a             0.985
#>  4 (129 x 2) whisky a             0.993
#>  5 (152 x 2) whisky a             0.989
#>  6 (161 x 2) whisky a             0.987
#>  7 (124 x 2) whisky a             0.995
#>  8 (126 x 2) whisky a             0.985
#>  9 (183 x 2) whisky a             0.986
#> 10 (193 x 2) whisky a             0.993
#> # ℹ 30 more rows