Faster resorvoir_sampling_single function (#788)

* Faster resorvoir_sampling_single function

* Update space_interaction_API.jl

* Update CHANGELOG.md

* Update Project.toml

CHANGELOG.md

@@ -1,5 +1,9 @@
 # main
 
+# v5.13
+
+- `random_nearby_position`, `random_nearby_ids` and `random_nearby_agent` are up to 2 times faster thanks to a faster sampling function.
+
 # v5.12
 
 - The `random_nearby_position` function is now much faster for GridSpaces.

Project.toml

@@ -1,7 +1,7 @@
 name = "Agents"
 uuid = "46ada45e-f475-11e8-01d0-f70cc89e6671"
 authors = ["George Datseris", "Tim DuBois", "Aayush Sabharwal", "Ali Vahdati"]
-version = "5.12.0"
+version = "5.13.0"
 
 [deps]
 CSV = "336ed68f-0bac-5ca0-87d4-7b16caf5d00b"

src/core/space_interaction_API.jl

@@ -367,23 +367,19 @@ end
 function resorvoir_sampling_single(iter, model)
     res = iterate(iter)
     isnothing(res) && return nothing  # `iterate` returns `nothing` when it ends
-
     rng = abmrng(model)
-    choice, state = res               # random position to return, and the state of the iterator
     w = max(rand(rng), eps())         # rand returns in range [0,1)
-
-    skip_counter = 0                  # skip entries in the iterator
-    while !isnothing(state) && !isnothing(iter)
-        if skip_counter == 0
-            choice, state = res
-            skip_counter = floor(log(rand(rng)) / log(1 - w))
-            w *= max(rand(rng), eps())
-        else
-            _, state = res
+    while true
+        choice, state = res           # random position to return, and the state of the iterator
+        skip_counter = floor(log(rand(rng)) / log(1 - w))  # skip entries in the iterator
+        while skip_counter != 0
+            skip_res = iterate(iter, state)
+            isnothing(skip_res) && return choice
+            state = skip_res[2]
             skip_counter -= 1
         end
         res = iterate(iter, state)
-        isnothing(res) && break
+        isnothing(res) && return choice
+        w *= max(rand(rng), eps())
     end
-    return choice
 end