Skip to contents

Get calliper

Source: R/get.R
get_calliper.Rd

Calculate the maximum distance between any two points (calliper/Feret diameter).

Usage

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

get_calliper_ids(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

  • get_calliper(): maximum distance as a numeric scalar

  • get_calliper_ids(): indices of the two furthest points as a vector c(i, j)

Details

Calculates the maximum distance between any two points on the outline. Also known as Feret diameter or maximum calliper distance.

Uses brute force O(n²) algorithm. May be slow for outlines with many points.

Note: get_calliper_ids() returns a vector, not a scalar, so cannot be used with measure().

Examples

get_calliper(shapes$cat)
#> [1] 229.9761
get_calliper_ids(shapes$cat)
#> [1] 39 80

# Use in measure() on minibot for the sake of speed
bot[1:2, ] %>% measure("calliper")
#> # A tibble: 2 × 4
#>   coo       type   dummy coo_calliper
#>   <out>     <fct>  <fct>        <dbl>
#> 1 (138 x 2) whisky a            1088.
#> 2 (168 x 2) whisky a             994.