Triangulation has nothing to say about two values at the same place, and
Qhull refuses outright. Real data does this constantly: a station occupied
twice, a transect that crosses its own track, coordinates rounded to a
printed precision.
Usage
collapse_duplicates(
xy,
value,
fun = mean,
quiet = FALSE,
fun_label = deparse(substitute(fun))
)
Arguments
- xy
coordinates, two columns
- value
one value per row of xy
- fun
function used to combine the values at a repeated coordinate
- quiet
do not report how many coordinates were collapsed
- fun_label
name of fun to use in that report
Value
A list of xy and value, with no repeated coordinate.
Details
So decide explicitly. collapse_duplicates() reduces repeated coordinates to
one, combining their values with fun, and says how many it collapsed.
Examples
xy <- cbind(c(1, 2, 2, 3), c(1, 2, 2, 3))
collapse_duplicates(xy, c(10, 20, 30, 40))
#> 1 duplicated coordinate collapsed with mean()
#> $xy
#> [,1] [,2]
#> [1,] 1 1
#> [2,] 2 2
#> [3,] 3 3
#>
#> $value
#> [1] 10 25 40
#>