Performs thinning of geographical coordinates using a hashing approach and rounds the coordinates to create a grid.
Usage
rounding_hashing_thinning(
coordinates,
thin_dist = 10,
trials = 10,
all_trials = FALSE,
euclidean = FALSE,
R = 6371,
seed = NULL
)Arguments
- coordinates
A numeric matrix of size (n x 2) containing the longitude and latitude of points, where each row represents a coordinate pair.
- thin_dist
A numeric value specifying the distance (in kilometers) within which points should be considered for thinning.
- trials
An integer indicating the number of trials to run for the thinning process. More trials may yield better results.
- all_trials
A logical value indicating whether to return all trials (`TRUE`) or only the best trial (`FALSE`).
- euclidean
Logical value indicating whether to compute the Euclidean distance (`TRUE`) or Haversine distance (`FALSE`, default).
- R
A numeric value representing the radius of the Earth in kilometers. Default is set to 6371.0 km.
- seed
Optional; an integer seed for reproducibility of results.
Value
A logical vector indicating which points are kept after the thinning process. If `all_trials` is `TRUE`, a list of logical vectors will be returned, one for each trial.
Details
This function applies a hashing technique to group coordinates into grid cells, allowing for efficient thinning based on a specified distance. It can run multiple trials to determine the best set of points to keep, or return all trials if specified.
Examples
# Generate random coordinates
set.seed(123)
coordinates <- matrix(runif(20, min = -180, max = 180), ncol = 2) # 10 random points
# Perform rounding hashing thinning
result <- rounding_hashing_thinning(coordinates, thin_dist = 10, trials = 5)
print(result)
#> [[1]]
#> [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
#>
# Perform thinning with all trials
all_results <- rounding_hashing_thinning(coordinates, thin_dist = 5000, trials = 5,
all_trials = TRUE)
print(all_results)
#> [[1]]
#> [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE FALSE FALSE TRUE
#>
#> [[2]]
#> [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE FALSE FALSE TRUE
#>
#> [[3]]
#> [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE FALSE FALSE TRUE
#>
#> [[4]]
#> [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE FALSE FALSE TRUE
#>
#> [[5]]
#> [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE FALSE FALSE TRUE
#>
# Perform thinning with euclidean distance
result_euclidean <- rounding_hashing_thinning(coordinates, thin_dist = 10,
trials = 5, euclidean = TRUE)
print(result_euclidean)
#> [[1]]
#> [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
#>