Code optimisation: ensure output are actually stored as integers

[jamesmbaazam]

As far as I can tell, the output contains only integers. You should make sure they are actually stored as integer. Not just at the end of this function but as the values are created and stored. This will be much more efficient in terms of memory and likely also computation speed.

set.seed(123)
chains <- epichains::simulate_tree(
  ntrees = 10,
  statistic = "size",
  offspring_dist = "pois",
  stat_max = 10,
  generation_time = function(n) rep(3, n),
  lambda = 2
)

lobstr::obj_size(chains)
#> 6.34 kB

lobstr::obj_size(vapply(chains, as.integer, integer(nrow(chains))))
#> 3.34 kB

^{Created on 2023-12-07 with reprex v2.0.2}

Originally posted by @Bisaloo in #122 (comment)