My goal is to ensure consistent output of a function that uses randomized computation.
- The code below achieves my goal but I believe the seed I set overwrites the user's seed.
# The output of kmeans is inconsistent accross runs
replicate(5, stats::kmeans(1:3, centers = 2)$cluster)
#> [,1] [,2] [,3] [,4] [,5]
#> [1,] 1 1 2 2 1
#> [2,] 1 1 1 1 2
#> [3,] 2 2 1 1 2
# Enforce consistent runs
consistent_kmeans <- function(...) {
set.seed(1)
stats::kmeans(...)
}
# Consistent
replicate(5, consistent_kmeans(1:3, centers = 2)$cluster)
#> [,1] [,2] [,3] [,4] [,5]
#> [1,] 1 1 1 1 1
#> [2,] 1 1 1 1 1
#> [3,] 2 2 2 2 2
- This restores the user's seed before exiting the function, but I get a complaing note in R CMD check:
consistent_kmeans <- function(...) {
old_seed <- get(".Random.seed", .GlobalEnv)
on.exit(assign(".Randon.seed", old_seed, .GlobalEnv))
set.seed(1)
stats::kmeans(...)
}
Created on 2018-08-09 by the reprex package (v0.2.0.9000
